Seems its time I once again bring back my diatribe on the topic of "X Mod is useless because Y does it better". There's already been a big argument about the overpoweredness of 'one block powerhouses', etc before as well in the community, as well as the dreaded powercreep into modding.
If we were purely to go on which mod's mechanics were the best for a function, then EnderIO, Mekanism, MFR, and Big Reactors in any combination would make pretty much all other tech mods useless. Thaumcraft and Blood Magic would, conversely, make all other magic mods useless. Powerful tools and items? TInker's Construct tools are insanely good, and Draconic Evolution is Draconic Evolution.
And this is only covering mods within the pack itself, everything goes out the door when you consider such things as Equivalent Exchange/Project E? If DartCraft was updated, that'd be another one.
There's much more to a mods inclusion than its 'best usefulness'. Adding variety, interesting way of doing things, interesting mechanics and looks, etc all matter.