Crap! I meant to post my list of mod suggestions too XD. But Infinity actually has all the ones I was gonna post. I have also had success adding Galacticraft to it as well, and I bet other mods from the current DD pack could be integrated. It'd be a crazy pack but would be a hell of a lot of fun. Horizons was also a lot of fun to play around with.
Edit: Aria already mentioned a lot of the individual mods I was thinking of, but I was also specifically thinking of:
Botania
Agricraft
Gendustry (bee stuff, love this mod)
Decocraft
Portal Gun
RFTools
Mystcraft (really think we should have this; it's not the server-killer it used to be, lots of fun could be had with it)
Immersive Engineering
Immersive Integration
FTB Utilities (really good claim/protection mod)
Draconic Evolution
Lots o' mobs (more animals, no werewolves! DINO DIMENSION) -
http://www.larsmods.com/Dimension Doors -
https://github.com/CannibalVox/DimDoors/releases/tag/2.2.5-test9 (not original author, linked from the official thread on minecraftforums as a continuation for 1.7.10 though)
Will post more if I can think of any.