I think the 'best guitarist in the world' debate is an interesting one, because the guitar is such a versatile instrument.
For example, if you mean in terms of innovation, producing a new sound that changed the music world, Hendrix has to be high on the list. But Jimi wasn't to everyone's taste and there's no point whatsoever trying to compare him to a classical guitarist in terms of 'bestness'.
My personal favourite is Steve Vai, who must surely rank highly in terms of technical skill and an ability to make his guitar produce really bizarre, unexpected sounds. And in the same genre, you can't neglect Joe Satriani, who taught Vai (and Kirk Hammett of Metallica, among others) to play.
If you've never heard (even of) Steve Vai, my recommended starting point would be 'For the Love of God', on the album Passion & Warfare. I saw him play this live at the Palais du Congres in Paris a couple of years ago and I'm not exaggerating when I say it was one of the most astounding performances I've ever witnessed.
That's my £0.0116123788* anyway
*At current exchange rates