there is no best, its all opinion. some people think that fastest is the best and dont care about tone, many people think tone is what makes the best not caring about speed. personally i think whoever can "say the right thing at the right time" is the best to me. some songs dont call for a fast solo or maybe the tone has to be set a certain way. i think the problem nowadays is most guitar players think speed is what makes you the best and they dont even take time to think about the melody or theme of the solo.