I know this has been done to death but why oh why does Jimmy Hendrix always turn up at no. 1?
The thing with Hendrix is that you'll often see him at no.1 on lists put together by peers too. His influence is undeniable, and added to the notoriety of his early death (the Cobain effect) his legacy has been secured. As with everything music related, such a list can only ever be highly subjective though. Personally, I care less for technical brilliance and virtuosity than I do the groove and simply the reaction the music generates (and I can't judge at all from a technical standpoint).
For that reason, my personal no.1 is Jerry Cantrell (Alice in Chains). No virtuoso, but the power of his riffs are incredible. The composition, distortion, timings - such a distinctive player. Rarely has a guitarist meshed so seamlessly with a vocalist than the Cantrell/Staley duo. Quality solo work, still releasing brilliant albums three decades in. He'll occasionally pop up on 'best of' lists, but wouldn't be an immediate choice for most - but a Cantrell riff is like music to my soul.
Other guys I have a fondness for:
Ritchie Blackmore (Deep Purple, Rainbow): particularly on the '76
Rising album, which is a masterpiece.
Tom Morello (Rage Against the Machine): inventive, brutal, responsible for some of the best riffs of the past 20 years.
Matthias Jabs (Scorpions): again not an obvious choice, but that band has some unreal material.
Michael Schenker (Scorpions, UFO)
Mike McCready (Pearl Jam)
Brian Robertson (Thin Lizzy)
Alex Lifeson (Rush)
I hear the thoughts on Mark Knopfler. Dire Straits, not a band I often play - nor Knopfler's solo work either - but his composition has a beautiful quality to it. I'd give a little nod to a couple of earlier legends too: Dick Dale, Chuck Berry.