Thanks for the shout out GFireflyE!
Since introducing the Monument XP mod, I can't bring myself to NOT play with it, as I love how it changes the game. Plus, it benefits the AI and players pretty much equally, which isn't an easy thing to do with most mods! Of course, I'm biased...
As for other recommended mods:
Snaking and River Bridges by Parrotmath - I think this is a must have.
The just released New Outpost Upgrades mod intrigues me, but it was just released today so I can't recommend something I haven't used yet. Nonetheless, I like what I see!
I have a bunch of other mods ready for installation as well, but right now I'm in modding mode so they aren't installed at the moment. I like to balance versus 'Vanilla' E:LH when testing my mods. Parrotmath and Heavenfall both have great mods, as do a few others.
One other minor change I play with involves the Elemental.Defs file. I've reset the minimum resources for city sites to 2 food/1 materials, and increased the cap from 9 to 15. To be honest, I've never seen a site with over 10 resources, though, and even the 8's/9's are still rather uncommon. This changes the 'balance' for city sites dramatically, and in particular this drops the Materials count for most city sites A LOT. I did try changing the caps for the starting city as well slightly, or just leaving them the same, but the game is ignoring that one. My starting cities now use the map values, not the 'minimum starting values'. Apparently changing the other values 'broke' the minimum starting values. As this changes the Elemental.defs file, though, I won't release it as a 'mod'. I hate changing others' core directory files if I can avoid it, especially this particular file.
There is a very nice resource mod that increases the resource counts for tiles, but I haven't played with it yet (still playtesting). It is a somewhat radical change from Vanilla E:LH.