No mention of Mr. Steve Vai yet? The man a genius on the guitar. Not only that but it is rare to find an artist who is willing to bring a teenaged guitarist on stage with him to play.
Other than that, I have to tip my hat to the Japanese guitarist Tak Matsumoto.
There are many great guitarists out there. The only one that is considered good by many that I simply cannot stand for a number of reasons is Yngwie Malmsteen.
Also... I know I will get flamed for this one... But speaking strictly as a musician... Hendrix was not that technically talented as a guitarist. (before you all jump at my throat...) I'm not saying he was bad, but he wasn't that fantastic either. What set him apart from the rest is that he was incredibly creative, and a genius. The same can be said of Frank Zappa, not talented technically, but so creative it more than made up for it.