Posted this in a similar thread in the BtS forum, it applies:
Fall from Heaven is the most popular by far. As was stated by IGN, the real competition for the warlords expansion pack was Fall From Heaven. This was not an overstatement. Though as stated Fall from Heaven is it's own game, in it's own right really.
For non game changing mods,
BUG and
Better AI are great. They leave the game the same, one just enhances the UI (BUG) and the other improves the AI (Better AI). Those two mods are essential in my opinion. Better AI is more of a bug fixer, sort of an unoficial patch; hell the firaxis people sometimes release info to those guys letting them know how to fix bugs that have shown up since the couple years of playtesting. As for BUG, well if you try it you wol't go back to the regular interface. Many modpacks include these two mods in them (I know mine does). In fact I don't know why anyone plays without these two mods, they should be the standard BtS game, played in MP, but alas it takes an official patch from Fireaxis to do this sort of thing.
As for your true mods, mods that change the game, it really depends on what you are looking for. I highly recommend my mod:
WolfRevolution or one of the components it is built from:
RevolutionCDM or
the Wolfshanze mod. Though if you are more into a radical expansion with dozens of new units and large gameplay changes (or enhancements depending on your point of view) take a look at
Rise of Mankind (itself built from RevolutionDCM--a great mod, I think it is the core of 3 popular modpacks). Another very popular mod is
Thomas War, it's not a RevDCM merge like WolfRev or RoM, instead it is kind of an extension of the official Next War mod.
Actually probably the best advice for you is to look through the Modpacks subforum and read through the threads. One piece of advice though. Make sure the mod you decide to download is stable. There are quite a few mods that you basically can't finish a game with, because they are unstable and will hang or crash after you play them for a while (a very frustrating experience, this is the main reason I built WolfRev from RevDCM and Wolfshanze, they are stable).
Wolfshanze is awesome, but if you're going for it, get WolfRev instead. All the new units from Wolf, plus the revolutions, civ emergences and so on from RevDCM. Best mod out there IMO, except perhaps FFH, but as CCRunner said thats more of a complete new game than a mod.
So WolfRev if you want Civ4 with cool new stuff, FFH if you want something completely different.
Thanks for the kind words
