For guitar, If I were to narrow it down to one, it would be Dave Mustaine.
If I cited a few influences, I'd say Megadeth, Crowbar, Nevermore, Vio-Lence, Testament, and Black Sabbath.
Vocals, I'd probably have to say Chuck Billy. Overall, alot of the 80's rough, angry sounding voices, like James Hetfield back in the day, maybe Phil Anselmo (I also tend to hit high notes similar to Halford like Phil did on Cowboys From Hell)