I have recently got a new PC and can finally run more than 20 mods.
I want to have a lot of options, but my world has got a lot of progress so far. Therefore I would prefer mods without world gen (or at least any world gen is kept to a new dimension, i.e. Twilight Forrest)
These are the mods I currently have (not including libraries or core mods)
Applied Energistics 2
Fast Leaf Decay
Flaxbeard's Steam power
Galacticraft (all modules)
Mekanism (not tools)
NEI (plus Addons and Integration)
Thaumcraft Node Tracker
WAILA (plus Harvestability)
I know of Carpenters Blocks,but tbh I never use them. They don't really fit with my designs.