Mods have their various visions.
Rhyes and Fall of Civilization went for more chronological accuracy/ historical realism.
Wolfshanze set out to improve both gameplay and historical realism ( He has an advanced degree in history). He no longer frequents CFC, others were trying to keep it going, but it may not be 3.19 compatible.
Legends of Revolution tried to make an unofficial expansion, and stayed true to the series. It incorporates much of Wolfshanze's work
( like coal navies), adds some really fun things like legendary units( which are sort of like world wonders& great generals rolled into one), and the super spies mod( which allows spies to gain promotions).
History in the Making tried to offer more of everything, including game speeds, map sizes, civics, 2nd UUs and buildings, wonders, corps, resources, religions, random events, victory types, special forces, air units( Grave is active duty USAF), and of course civs and leaders. It also changed a lot of things including traits & tech requirements in a re-balancing effort. It's a lot of extra stuff, great gameplay, but it's different from the original/official. ( and no, it doesn't add as much stuff as Rise of Mankind )
BUG is an Unaltered Gameplay mod, which improves the interface without changing the game. Influence Driven War is a mod in which combat affects control of a tile. Dale's Combat Mod affects bombardment ( Dale was an artilleryman ). These are popular inclusions found in many modpacks, including Legends of Revolution and History in the Making ( the two modpacks I play more than the official version ).
I hope this helps.