Windpower:
The problem with wind-power is that by its very nature you need LONG DISTANCE power transfers. You need to move your EU's through a very long cable which means a lot of power loss. If this problem were solved, Windpower would be a great choice.
Problem 1: We need a way to convert LV to EV and back again cheaply. The current setup requires a lot of transformers to convert between the two as well a lot of highly lossy refined iron cable. Your best bet is the not even insulate it because that is a metric tun of rubber required to fully insulate it. You are also going to need a heck of a lot of this cable.
Possible solution: Make a transformer between LV and EV. Try bronze cables (and fix the bronze formula to yeild 4 dust. How does 4 dusts turn into 2 dusts? If you wanted to somewhat accurate on how bronze was really made it would be 8 copper to 1 tin (actually its should be 19:1 ratio but you can't do that in minecraft)). The EV transfer cost should be cheaper, if we are trying to be realistic. After all in the real world we do use EV to transfer power precisely because it is far more efficient.