There are three general tracts for reaching end-game. These are obviously loosely defined, and you'll likely use aspects of each, but this should hopefully provide an early guide for moving forward.
High Tech: Thermal Expansion/Dynamics, Applied Energistics, Solar Flux, Big Reactors, Mekanism, EnderIO
Industrial: Immersive Engineering, MineFactory Reloaded, ProjectRed, BuildCraft, Railcraft, Forestry, IndustrialCraft 2
Magic: Thaumcraft, Blood Magic, Sanguimancy, Witchery, Botania, Twilight Forest, Better Furnaces
Detailed pack info: http://www.circlecraft.info/datpack/
High Tech: Thermal Expansion/Dynamics, Applied Energistics, Solar Flux, Big Reactors, Mekanism, EnderIO
Industrial: Immersive Engineering, MineFactory Reloaded, ProjectRed, BuildCraft, Railcraft, Forestry, IndustrialCraft 2
Magic: Thaumcraft, Blood Magic, Sanguimancy, Witchery, Botania, Twilight Forest, Better Furnaces
Detailed pack info: http://www.circlecraft.info/datpack/