If we are looking for the most under rated band ever it HAS to be these guys, why they have never made the big time is beyond me
https://www.youtube.com/watch?v=vw8WfPiKgKs
Poco, lived in the shadow of the Eagles and had two band members poached by them. Poco were a better band imo, if not as slick
Wishbone Ash, really under rated band
The Zombies, cutting edge music back in the day, probably too far ahead of their time