I know it's an old topic, but I have a few that come to mind.
Claudio Sanchez and Travis Stever of Coheed and Cambria. Got to see them play live, and although they are getting some recognition now, they are WAY underrated. They're rhythms and harmonies are tight, and their solos are spot on and creative. I played in a band that covered a lot of their older stuff, and even that stuff is insanely complicated to really pull together live, listen to their songs "The Crowing" "A Favor House Atlantic" and "The Velorium Camper II: Backend Of Forever" to see what I mean.
Also Jani Liimatainen former guitarist for power metal band Sonata Arctica. His rhythm work really impressed me, simple but effective. And his solos are pure technical and musical genius. Listen to his solo in their song "Weballergy", it's just awesome...