How old are you? Hell I'm 31 and I feel like they're underrated
I like the Guess Who but they are hardly the most underrated band of all time. They sold millions of records and had #1 singles in their day, and even now are probably still a draw on the casino/oldies circuit
An underrated band is somebody like The Silos, who helped invent alt.country with their classic album Cuba
(released three years before Uncle Tupelo), but never got any commercial sales or radio airplay and today have trouble selling 50 tickets to a bar show, at least in BR.