As a ham and egger guitar player for 15 years or so, May is being severely overlooked in this thread, and I dont even like Queen. Love Jimi as a guitar player and his music, he was a natural talent, but lacked technical skill and a lot of his songs just use chord exaggerations and Jimi really stayed in his comfort zone with chord progressions and soloing. I'd personally take Jimmy Page over both of them if we are simply judging guitar playing.
Jimi died way too young. The sky was the limit for him had he stayed alive and especially had he learned more about understanding music theory. With that being said, what he was doing in the 60's was totally revolutionary. I think his mark on music is more that than his technical skill on the axe. He accomplished so much in such a short time. Makes ya think how much brilliance we missed out on with his early passing.