- Archivist: +50% city research production when producing research here. Only really useful if you're willing to have one city which is basically undeveloped that only builds research infrastructure (which isn't very practical, given how long it would take to build the stuff if you don't have good production levels).
- Oracle: +1 essence in city. I consider this to be in general the best Conclave upgrade at this level.
- Scroll Scribe: +20% to city research production; provides Blizzard Scrolls, Return Scrolls, and Summon Air Elemental Scrolls to shop. I'll take one or two of these in convenient locations so that I have quick and easy access to Blizzard Scrolls if I want them for use in any wars I'm fighting, but generally I'd rather have an Oracle.
Oracles are good, Scroll Scribes are decent, Archivists can be circumstantially useful. I'd rather that the Archivist gave a bonus which was always in effect in addition to (or in place of) the continuous production bonus, but otherwise this is a decent set.
- Academy of Revelation: +10% faction research production. Good when I have highly distributed research, bad if my research is highly concentrated and badly hampered by unrest. Widely distributed research is likely to benefit more from this than from the Tenfell University even if my research is suffering badly from unrest.
- Amethyst Vault: +2 crystal production per season. If I haven't had much or any crystal income up to the point where I'm offered an Amethyst Vault, chances are I haven't bothered researching much of anything in the magic tree, because most of what that gives me requires crystal which I don't have. I don't find this particularly useful.
- Tenfell University: this city's research production is unaffected by unrest. Only useful for small empires where removing unrest research penalties on one city is a bigger bonus than increasing the overall research bonus by 10%. I'll pass. I might go for it if it offered a set of scrolls like the Scribe does, or if it gave me e.g. Wands of Fireballs.
Tenfell University could use improvement relative to the Academy of Revelation, and Amethyst Vaults come somewhat late, likely after I'm already a fair ways into whichever military tech path I chose to pursue based on Iron Deposit and Crystal Crag availability, which means that it's either a minor bonus to my already sufficient for my purposes crystal economy, or it's not useful enough to justify diverting the amount of research necessary to bring Magic-based equipment up to about the point I'm at with Warfare-based equipment. If it's my only reasonable source for crystal, I'll take it so I can use trinkets, if not I don't want it. Academy of Revelation is the only really useful one here.
- Hedigah Bathhouse: +1 Water Mana; city unrest reduced by 30. This is about on par with the Pyre. Whether I take this or the Pyre depends on whether or not I want more Fire or more Water shards at the moment, and to a much lesser extent on whether or not I've adequately managed unrest to this point of the game.
- Pyre of Anniellum: +2 Fire Mana. See above.
- Tower of the Magi: trained units receive 10 extra spell resistance; city is immune to strategic spells. 10 spell resistance is useful at the point in the game when you can get this? Does anyone normally train units in high-level Conclaves rather than high-level Fortresses (or even low- or mid-level Fortresses)? The strategic spell immunity might be nice, but I'd rather have a Pyre or a Bathhouse. I'll only take this if I'm really having significant difficulties with spellcasters that I think can be solved with an extra 10 spell resistance over and above the 10 spell resistance I can get in unit design, and think that the loss of the Fortress bonuses is more than compensated for by that extra 10 spell resistance, which strikes me as a rather unlikely situation.
Tower of the Magi really suffers in comparison to the Pyre of Anniellum and the Hedigah Bathhouse if you're using any spells that have any dependency on Fire or Water Shards, and additionally Conclaves aren't my go-to locations for troop training - if they aren't building infrastructure, I'd rather have them producing research than units, because Fortresses can turn out better units faster than Conclaves can in most circumstances. I also don't think I've ever been in a situation where the extra 10 spell resistance would have been that useful. Pyres and Bathhouses are good as-is.
- Infirmary: units trained here receive trait "Endurance I" granting them an extra 1 health per level; units stationed in this city heal by an extra 10 health per turn. It's useful for tanking units and for healing up quickly after a battle, so it's okay, but not terribly great. If I'm making a secondary or tertiary training fortress, a border fortress, or an unrest reduction fortress, I might choose this.
- Strike Garrison: units trained here receive the "Impulsive" trait, granting them +2 initiative. My preferred upgrade at this level.
- Watchtower: units trained here receive trait "Charge" granting +1 move and +2 attack on their first turn in a battle; city defense force increased by 1 catapult. Fine for border defense, though I think Impulsive is better than Charge most of the time, and I can get Charge during unit design if I really want it. Like Infirmary, this is an option for a secondary or tertiary training fortress, a border fortress, or an unrest reduction fortress, but not really for my primary training fortress.
All of these are about equal, though Strike Garrisons and Watchtowers provide traits which is better for offensive troops and Infirmaries provide a trait which is better for the tank line (as long as you can preserve the tank line long enough for it to pick up a few levels, anyways). Watchtowers can be replaced by picking its trait during unit design, but otherwise I don't have any real objections to any of these. I would kind of rather that one of these were switched with one of the Fortress 4 upgrades, but I see the reasoning behind forcing a choice in how to train the elite troops.
- Gallows: this city's production is unaffected by this city's unrest level. This does the same thing as the Empire improvement "Slave Pens" without the production bonus. If I'm playing a Kingdom, maybe. If I'm playing an Empire and am not unwilling to build Slave Pens, no way.
- Mining Guild: +2 metal production per turn. I'll pass on this one for all the reasons given above for the Amethyst Vault, with the added reason of Iron generally being a far more common resource.
- Prison: -10 unrest in all the cities you control; -1 growth in this city. -10 global unrest is nice, -1 growth in the city is not. Depends on how useful I think getting the city up to the next level will be, and whether or not I think that -10 global unrest is particularly helpful for me right now or in my short-term plans (long term plans include Onyx Thrones, which are greatly superior).
Gallows is useful to Kingdom players, but the Prison basically serves the same purpose on an empire-wide level, and the Slave Pens available to Empires are strictly better than the Gallows; Slave Pens can additionally be built in every city within an Empire. Mining Guilds suffer the same problems as Amethyst Vaults, with the additional problem of Iron being so much more abundant. In the relatively rare case that I lack sources of both Iron and Crystal, I'll go up the Warfare tree for improving my military so Mining Guilds are slightly useful as backup metal sources, but they aren't useful as supplements to existing sources of Iron unless you're really desperate for metal. On the whole, I'd say that Prisons are the best choice here, though that growth penalty hurts your ability to get to the next level, where the good unrest reduction structure can be found (on the other hand, the growth penalty can be counteracted with a single Consulate in an outpost or made more or less negligible with Sovereign's Call, so it's also not terrible).
- Great Arena: units trained here receive +1 attack (note that this probably only applies to units with nonzero base physical attack) and +3 health (both of these apply per-figure). This would be my favored choice for unit training Fortresses.
- Onyx Throne: -30 unrest in all cities controlled by the player. This would be my favored choice for Fortresses which are not used as training centers.
- Underforge: +1 Earth Mana; armor production cost is halved in this city. How often does anyone want Earth Mana? The armor production cost reduction is okay, but isn't as good as the Great Arena bonus in my opinion unless I'm more interested in quantity than quality.
Great Arenas are good for troop training centers, Onyx Thrones are good for anything else. About the only situation I can think of where I'd want an Underforge is if I'm using metal equipment on throwaway troops and I want to be able to produce them slightly faster, though I suppose that an Underforge Fortress producing elite units would churn out elite units faster and at only a very small loss of power relative to Great Arenas, because by the time Underforges could reasonably be expected to exist in my cities the production costs of Leather Armor should be negligible, and I'd rather spend crystal on weapons and trinkets than on armor, and on elite troops rather than fodder troops.
- Guild Grocer: +5% health for all the player's units. Probably the best bonus Towns get.
- Slums: +3 growth in this city; +5 unrest in this city. Only useful if I want a target for Sacrifice or Blood Curse, as population isn't very useful except at certain breakpoints. I'll pass on this for all of my cities in most games.
- Guild Warehouse: +50% gildar production in this city when producing wealth here. Sort of useful for one or two gold factories, not very useful for much else. I'd rather take the Grocer.
Bad set; Guild Grocers are very useful in all situations, whereas Slums and Warehouses are at best circumstantially useful. I would go so far as to say that the Guild Grocer is the single best improvement Towns offer, and might be the best level-up improvement in the game, especially since the bonus stacks with additional Grocers.
- Almshouse: +1 Fame per season. By the time I get this, I don't need more champions. I'll pass unless I'm playing an Altar Henchman strategy.
- Embassy: the unrest penalty for empire size is negated in this city. Not particularly valuable to me.
- Governor's Office: +1 production per material in all cities of this player. I suppose it's sort of useful, and more helpful overall to my empire than the others. Nothing fantastic, but not terrible.
Bad set; I don't like anything offered here, though I'd sooner have the Governor's Office than anything else. Generally if I have two or three champions available for leading my armies and have one or two available for sitting in towns, I don't really want any more of them, so the Almshouse isn't useful (I'll have three or four champions long before the Almshouse even nears availability in my normal games). Embassies just try to reduce unrest in the one city type that doesn't really need to have unrest reduction to fill its primary purpose, and moreover I ought to be managing my empire in a way that keeps unrest at a reasonable level without needing this, because if I need this in a level 4 Town I probably also need it all of my Conclaves and Fortresses, which have greater need of unrest reduction than Towns do. Thus I'll take the Governor's Office since that's actually useful, even if it's not very useful.
- Guild Lendinghouse: +2000 gold upon construction; no ongoing bonus. I'll pass. I only use gold for paying wages, rushing one or two structures every now and then, and filling up missing equipment slots on champions I'm using. I don't need 2000 gold dumped into the treasury.
- Guild Tribunal: +2 production per material in all cities of this player. Good for my empire, but not spectacular.
- Mint of Ruvenna: +5 gold production per material in this city. Like Warehouses, it's sort of useful for one or two gold factories, but not for much else. Small amounts of gold just don't have much value, and even +5 gold per material isn't that much when you consider that you're only getting your tax percentage out of it.
Bad set; by the time the Lendinghouse is available, buying weapons for even two champions can easily blow through the whole bonus, and it doesn't offer any ongoing gift. If you set up Consulates etc to boost the growth so that you can get here at a point in the game where the gold is valuable, then maybe it'd be worthwhile. Mints of Ruvenna suffer a similar problem, with the added 'bonus' of being affected by your tax rate, though they can be used as the basis of a sustainable economy, unlike Lendinghouses. Rushing production and buying champion equipment is so expensive by the point you can usually get these things that they just aren't really worthwhile. This means that the Guild Tribunal wins by default, though by the time you get it, it isn't that great either.