I have been playing The yogscast complete pack (using ATL launcher, meaning it auto installs the mods FOR YOU) and there is SOOO much stuff! Im focusing on the magic/witchery and bees. I also LOVE the electric fences! Take that creeper!
I play the Yogscast ones on FTB, technic and ATL. They have mod pack support so if you have an issue they can help you, and they check the packs regularly to make sure they are working.
The issue with ATL is that you need a 64 bit computer with 64 bit java. My computer is a custom built gaming computer (still needs a few upgrades but we are getting there) so I do have the 64bit windows and java.
FTB its the most computer friendly one.
If anyone needs help with these let me know, my brother and I are good and fiddling with them. And if everyone gets on the same modpack we can hop on a server and play :)