For creative, if absurdly inefficient, power, you could use whatever Bluelectric power source you want (Is it Saice who's a fan of this one?), and run that into a BT engine for some MJ, which can them be converted into EU.
For early-game power, popular options include Geothermal Generators or solar panels for EU (I've heard that aluminum cans are handy for transporting lava), and steam engines for MJ. I would recommend those of Thermal Expansion over Railcraft's Hobbyist steam engine, as they produce more power and have no warmup time. I think that Railcraft's engine is a little more efficient than TE's, once it warms up. And from what I've heard, that warmup is a significant efficiency hit, as you probably won't be running the engines for very long at a time, until you have a Redstone Energy Cell.