For me, there is no one "best" guitarist.

There ARE those in their genres that ARE masters of their trades.
When I watch videos of SRV (RIP) doing sound checks and improvising its hard to imagine anyone better.
Then I see clips of him, Albert, and BB take it over the edge every time they ever did Texas Flood.

Flash back to Pagey just dismantling everything you ever thought you knew about playing guitar, then he "goes to the bow" and ices the cake.

I remember the first time I heard Edward's lead in on VH first album. Thought my head would explode.

I can listen to any of those guys, plus beck, jack White, all the way back to Robert Johnson.
These are men whom the guitar has no secrets.
The genre does not matter to me when I listen to guys at that level.