I like a whole lot of guitarists but the ones that actually influenced me as a player and helped me to form my own style are:

Marty Friedman
Jason Becker
Dave Murray & Adrian Smith
Joe Satriani

I only started listening to Yngwie lately and I can't believe I deprived myself for so long! I'm getting a lot from his chamber orcehstra album, really nice compositions and the guitarwork is not too in your face - the only other album of his I have is the "best of" instrumental album, also becoming a strong influence.