It depends on what I want to do that day. I havent delved in Thaumcraft as much as I'd like to (dont wanna muck up my place!) but
Millenaire for questing/people that arent dependant on me completely for their survivial
MineColony for when I want to play "island survivors" (*even have a seed just for it, starts with 1 tree, some grass, and 1 stand of sugarcane on another smaller island)
Mo'Creatures because I love horses and like having more variety to the local fauna. Also want a herd of zebras. yaaaaay zebras!
So overall I'd say mocreatures because ore creatures. But it depends, really.