First you need to clarify yourself about what is the best.
A player can be the best on a technical level but whats he's playing is so intricate and complex that it is not pleasant to hear for many people, thus it may not be the best player because despite his skill, he doesn't play much hear candy stuff. One example of this would be Yngwie Malmsteen (skip to one minute):
On the other hand, you have guitar players, that with the most simple chords can make a classical song that millions of people love. Like Eric Clapton with Tears in Heaven. Clapton's technical skill on the guitar is way below that of Yngwie's, still he's playing a "better" melody that more people like the best, thus, he's a better player than Yngwie.
I think you're referring to the second point of view of "best guitarist", and if so, that is questionable. It comes down to one's preference about who's the best.
Now speaking at a technical level, in my own opinion, I have never seen such a good player as the Brazilian Tiago Della Vega (skip to the 2 minutes mark)
