Well, certainly not less known, but maybe less played would be John Scofield. And on allmusic.com, they list Scofield as, "...One of the "big three" of current jazz guitarists (along with Pat Metheny and Bill Frisell), Scofield's influence grew in the '90s." Hahaha...
There's also John Abercrombie, but I have to be in the right frame of mind for that stuff. And, since I can only think of John's right off the bat, try John McLaughlin. I'm a Pat Metheny fan, myself.
To do some research, head out to
www.allmusic.com. Put in your artist name, then when you get their page, scroll down a bit. You'll see a few cool sections like Similar Artists, Followers, and Performs Songs By. This is a great resource.