(If you use unit packs, it's worth being aware that you also need a pack file which causes the names of the new units to appear in the game. Large mods such as Darthmod, Imperial Destroyer and Imperial Splendour add units and make other changes to game-play. I had a lot of fun using Empire Total Factions to play as Venice, while using Pom's Italian States Mod, for example.
There are also unit packs which add specific units or units for groups of factions. Swiss Halberdier's Additional Units Mod adds a lot of extra units: (AUM-EMP)-3-4-updated-13-2-15. I agree that more variety between factions would be a good thing.
