I quite recommend Mekanism; its a hell of a lot of fun to play with, and its got the best passive power generation I've ever encountered. For early-to-mid power, you can't beat it. Oh, and universal cables that simultaneously carry Joules, RF, MJ, and EU. There might be another in there, I don't quite remember...I know there's 4 different tiers now: basic (200 RF/t), advanced (800 RF/t), elite (3,200 RF/t), and ultimate (12,800 RF/t). The values you see in-game, by default, are Mekanism's own Joules, but I converted them to RF since that seems to be the most common power type amongst the ones Mekanism can use. Oh, and you can tweak the Joules:EU,RF,MJ,etc ratio in the config!
Odd question, but would anyone here be interested in a thread detailing my ongoing research into modded Minecraft energy sources and their interactions with one another? I kinda started to help keep my note-taking skills sharp, and was wondering if anyone here might find them useful.