I used to hate tekkit for its content, now I hate it for the fact that the people putting it together refuse to respect the mod authors who don't want their mods used
Moreover they only made the mods work together, but didn't put any real effort into integrating them. Duplicate resources and functionality overcomplicate things - a new player won't know what the forget is going on when you say "engine" because Redpower machines, IC2, Buildcraft, Forestry or what the forget else
(Also EE2 is bad and it should feel bad)
Like if you looked at my mod list (okay I know, I won't link it this time because it's obnoxious plugging my content) you'd see I don't include IC2, but it's not because I don't like IC2 - I just think it's redundant. You don't need it - Buildcraft and RP2 have their own power systems, Metallurgy has essentially a macerator and Thermal Expansion has something similar with some other bonus functionality, RP2 has blulectric furnaces and TE has a BC-powered furnace too. IC2 just isn't needed, as cool as it is, and I prefer the other versions because the crafting is a bit less complex.
I could run a tumblr blog where I post a rant a day about minecraft mods, wow