Yes, The Guess Who had great popularity, but are definitely due greater appreciation, IMO. There is a push now in their hometown of Winnipeg, Manitoba to get them inducted in the R&R Hall of Fame. They were inducted into the Canadian Music Hall of Fame in 1987.
BTO was also inducted into the Canadian Music Hall of Fame in 2014, but is not in the R&R Hall of Fame either.
I have seen both groups in concert. My wife and I also had the singular pleasure of listening to a personal, up-close, piano medley by Burton Cummings around twenty-five years ago. We came upon him playing on the baby grand in the mezzanine area of the Westin Harbour Castle Hotel on Toronto's waterfront, while staying there one weekend. It was one of those "Are you who I think you are?" moments. His reply was, "Yes, it's me!" We sat and enjoyed a wonderful mini-concert for the next half-hour or so, as the crowd grew to about a dozen. He was very laid-back and personable!
GUESS WHO should be in the Rock & Roll Hall of Fame: petition | Winnipeg Sun