Underrated
Bruce Springsteen. His technique is very basic, he is not a virtuoso by any means, but back in the day he could do some really gutsy and powerful guitar playing.
Pep Sala. Nobody knows him internationally, but he was the guitarist of the mythical catalan rock band Sau. And in my opinion he made one of the most beautiful solos in the history of "el Rock català".
Pino Palladino was the bassist in the records of Sau from this era. He is famous for have worked with The Who, John Mayer, Simon & Garfunkel or Jeff Beck.
Overrated
Bonamassa. He is a hell of a guitar player, but I find his music really boring and unoriginal, and at the end the music you do is the most important thing.