Oh wow, there are just too damn many good to pick one that stands out.
I mean, The Prodigy har been my gods ever since Experience or What Evil Lurks. The Chemical Brothers put on the best live performance I've ever seen. Their music is otherwordly. Moby is a savant. Fatboy Slim and all his other alter egos (like Pizzaman) are just too damn good. Aphex Twin is a genius, pure genius. Basement Jaxx and french electrohouse .. few other styles pep me up as much as they do, just a huge smile all day long. U96 .. man, also just genius. T.I.P., Astral Projection, and so on and so forth .. I love EDM.
I don't know man, too many that are too good to make a decision. Also, I can't even decide on any particular sub-genre to EDM that I prefer the most.