Both are amazing guitarists, whose lives came to unfortunate and early endings. Although SRV was quite the outstanding musician, Jimi lead the revolution of guitar-playing with distortion, and influenced tons of musicians to this day. So, Jimi it is I suppose.
By far Jimi he has so many brilliant songs and he even make sthe feedback sound beautiful (Willd thing@monterey). The range of music he played he could put you in a trance, make you laugh or (impressively) actually think about the world we live in.
Well, I'd say that stevie's guitar has a much better sound than jimi, and I prefer to listen to stevie over jimi, but as far as skill at guitar goes, I'd have to say that jimi is better. jimi also plays a much wider variety than stevie.