Betrayer + adventurer is fun
Betrayer + wealthy is fun, just not as dramatic
Wealth + civics (rush) is fun, but limited
Beastlord is fun - 0 upkeep umberdroths.
Some of these could be OverPowered, but really each has an opportunity cost and a risk.
While you're focusing on champion research you may not be doing other things - and the AI may outstrip you in terms of cities, armies, mana, etc.
I've had games as betrayer+adventurer (shadow in stormlands) where my entire "faction power' was comprised of the 12 champions I was able pick up - on easy (doh) that worked out well.
I'm replaying the strategy on ridiculous and while I have 8 champions and i focused on exploration - the AI is outstripping me in terms of power. Plus its really tough to level up/gear 8+ champions. Its easily blown me up on research, so I'm even more behind (although tireless march is a great asset by itself).
As beastlord I've had awesome armies of umberdroths, hoarder spiders, great wolves and archers.
I've also had entire games where there are only a few critters to pick up. With masters affliction mod the area is so dangerous its difficult to explore and find critters to pick up. And spiders can't be charmed.
Heroic + henchmen + questmaps is still the most OP IMO although kind of boring after the first run of it. I don't think I would change any of the above traits.
Some of the others are a bit lackluster (noble) but other passive skills just keep on giving - i.e. armorer which could easily be more beneficial long term..just a bit more boring.