[Nightwish]

It depends on what you mean by "best." For instance, some of the guys mentioned in the OP were highly influential, highly stylistic, but pretty average when it comes to technical ability (most notably, Jimmy Paige and Jimi Hindrix). Other players in that category (lots of style and influence, average technical ability) would include Tony Iommi and Alex Lifeson.

It's impossible to answer a question about which guitarists are "best," because there are just too many different dimensions to compare -- unique and individual style or personality, influence, technical ability, etc.

Tons of individual style, but only average or slightly above-average technical ability

Jimmy Page
Jimi Hendrix
Alex Lifeson
Tony Iommi
B.B. King (and most other "great" pure blues players)


Tons of technical ability, but their style doesn't really stand out

Glen Tipton
Timo Tolkki
Warren Demartini
Arian Smith
Jake E. Lee
Adrian Vandenberg
a ton of thrash, speed and power metal guitarists


Distinctive style and lots of technical ability

Steve Vai
Yngwie Malmsteen
Akira Takasaki
Randy Rhoades
Dave Murray
John Petrucci
Joe Satriani
Eric Clapton
SRV
Al Di Meola
Eddie Van Halen
Kai Hansen
Andre Olbrich
Luca Turilli
many "great" jazz guitarists

Of course, those are merely my opinions, and those lists are by no means exhaustive. And I'm sure a lot of Maiden fans might take issue for me not putting Adrian Smith and Dave Murray in the same catagory, or not putting Janick Gers on the list. I didn't exclude Janick because I don't think he's good, but only because I haven't listened to enough of his work that closely to really know which category to put him in.