mods which speed up your early game
natura
Tico ( alrdy mentioned)
mods which let you build neat stuff
chisel, carpenter's blocks, again Tico for transparent glass
mods which allows you to automate things ( add them all)
applied energistics, extra cells, logistic pipes ( my favorite )
terrain generation mods
Biomes o plenty, ATG
Magic mods
Thaumcraft 4, thaumic tinkerer, thaumic tinkerer KAMI, forbidden magic, technomancy
I would also add forestry (mbe binnie's mods and gendustry if you like bees and trees)