the best would be the battery. you can use the power source that feeds the fuse box as well it all depends where your trying to run the l.e.d.s but if you use either or those you will need to fuse them
Put a fuse in one of the unused positions in the power distribution panel. Crimp a terminal on a wire and plug it in from the bottom. Kinda like adding a circuit in your house. The power distribuiton panel (fuse box) under the hood is bussed.
If you look at the rear of your fuse box under the hood (pass side) you'll see the battery cable attached to a stud where it feeds everything. I hooked up the power wire for my RetroSolutions HIDs to this stud.