Obviously a very subjective category, but my faves that are actually still around today are:
Andy Timmons (amazing versatility, passion & technique, WAAAYY more than "Just another shredder")
Guthrie Govan (brilliant!)
David Gilmour (he's David freaking Gilmour, 'nuff said!)
Jeff Beck (see David freaking Gilmour comment!)
Michael Schenker (when he's not falling-off-the-stage-drunk, he's still one of the best rock guitarists ever!)
Alan Holdsworth (seeing him live in '94 was one of the most jaw-dropping experiences of my life)
Tommy Emmanuel (nice to see all the love Tommy's gotten here! I've loved his stuff since I first heard "The Journey" on Larry Carlton's old jazz radio show)
Mikael Akerfeldt (for being one of the few truly groundbreaking musicians in heavy rock today)
Steven Wilson (see Akerfeldt comment)
Eric Johnson (Amazing on so many levels, STUPID tone, and the guy who co-designed my sweet Strat!)
Paul Gilbert (again, WAAAYY more than just another shredder!)
Ty Tabor (one of the most tragically underrated cats ever, although why such a brilliant soloist has basically sworn off solos for the past three records baffles me to no end!)
Eddie Van Halen (without argument, the most influential player since Hendrix, and a fantastic songwriter in those lucid moments between drinking binges)
Jimmy Herring (Aquarium Rescue Unit pwns!)
Warren Haynes (brilliant with or without a slide, incredible passion and soul, ridiculously sweet tone)
Sonny Landreth (superhuman slide wizard)
Derek Trucks (brilliant musician, possibly Duane Allman reincarnated... plus, I know his dad! lol)
Andy McKee (just plain sick)
Alex Skolnick (for my money, still the best soloist of the seriously heavy bands. I got to see the Alex Skolnick Trio a couple of years ago, too... very cool, check 'em out if you get the chance)
Vinnie Moore (one of the most musical of the uber-shred school, also one of the nicest guys you'll ever meet)
Steve Morse (brilliant in a wide variety of styles, his classical playing is stunning and vastly underrated, also, along with Vinnie, one of the nicest guys you'll ever meet, and a guy who will talk to you forever about music!)
Of the all-time greats who aren't still around:
Stevie Ray Vaughan (I got dragged kicking and screaming to see him in '89, and it changed my life! The guy was a fucking witch and NO ONE before or since ever played the blues with that same lethal combination of authority, power, passion and sheer SOUL)
Jimi Hendrix (turned the guitar playing world on its ear like no one before or since)
Randy Rhoads (easily one of the greatest rock n roll tragedies ever simply because he never even got to hint at his full potential)
Michael Hedges (without this guy, cats like Andy McKee wouldn't be who they are today)
Shawn Lane (an absolute FREAK... I was lucky enough to witness a dual clinic he did with Andy Timmons many years ago, and still can't get over it. The guy walked in the door of this tiny music store, didn't say anything to anyone, sat down at a beat up old upright teacher's piano and started BLAZING Franz Liszt. Stunned silence permeated the room for the ensuing five minutes! The jam with Andy Timmons at the end of the clinic was freakin' EPIC...)
I'm positive I'm forgetting several guys, but that's it for now!