I think Joe Bonamassa is a total Stud when it comes to guitar. He is one of the most knowledgeable and creative students of guitar today. I have always been in awe of his tremendous talent. If I had to pick only one super star of guitar today that is top of all the people I hold so high in opinion of, it would be Brent Mason. I don't say that Brent is better than Joe. I just say that Brent Mason's style is more in tune with the direction that I am in tune with. I have tried to copy certain licks from them both. I guess you could say too that Brent's style more resembles the pinnacle where I am trying to get too and knowing that I never will. Don't get me wrong, Joe Bonamassa is a true "Monster Guitar" player. He is certainly number 2 or 3 in my top 5 of the many many guitar players that I am in awe of.
For me, 'The Man' is just an expression, meaning, I take Bonamassa's opinion seriously. But I don't think there's such a person as 'best guitar player'.
There are lots of them!
I don't want to sound preachy, and hope I don't, but I think it's a topic worth discussing, and besides, I make my living in the arts and have a perspective that might be a bit different than most folks'. In any case, it's an interesting topic.
In my sessions, I've employed players with astounding chops who've blown my mind, each in their own way, and who've toured with famous artists and bands. They're all different. They all do great things. I respect them all.
As a band leader, performer, session player, writer, producer and singer - all of which involve different (related) skills, Bonamassa is certainly worthy of a high degree of respect. I'm sure that's all he'd even want. So is Brent Mason in a different way, and so are lots of others in their ways.
Perhaps trying to answer the question, "Who's the greatest artist?" does a disservice to the art. Everyone who's great carves out their own space, absorbs influences from those who came before, has unique tone - I could go on and on.
I can't say for sure what art is, but I'm pretty sure there isn't is some kind of competitive game, with rules, statistics, and championships, This is why I think awards shows are kind of silly; they're just promo bs.
I have my favorite artists, of course. But there isn't much point in creating a pecking order for them, or anyone else, really.
For me music is a celebration of what's possible artistically, and there are so many people of merit making it that it's actually a little daunting to put my own stuff out there in the world - I know it's inevitably going to be compared to what's already there (well, what genre and what composer or band does this sound like and blah blah) because so little is taken on its own merits. However, I think art should be taken on its own merits.
It's a difficult enough thing to be in the arts professionally. Pecking orders just make it harder.
"Then why do you say your orchestral work sucks when you post it?"
"Oh, well, because it pretty much does.
But I'm working on it!!" 
