I guess I will represent metal, ha ha. For me, right now its Jeff Loomis of Nevermore. Just listen to that sick solo.
I also like Stevie Ray Vaughn. That guy put so much feeling into his playing. I know he's not metal, but still one of my favs.
Tony Iommi, just for creating a new genre of playing. He is the father of heavy metal.

The hardest thing for me to play is Meshuggah. Damn complex polyrhythmic patterns. 10/16,10/16,10/16/,4/16,10/16,10/16, 8/16, 36/16 rhythms are hard to follow when the drums and bass are playing 4/4 time then 5/4. Follow along if you can.

Meshuggah