One from left field here but trust me -
Maggot Brain by Funkadelic. Eddie Hazel was told to play like his mother had just died and what he came up with was incredible.
I can't believe nobody mentioned Elliott Randall's guitar solo in Reelin' In The Years. Wow, I thought was accepted as one greatest of all time.
Not bad for a "middle of the road" group.Goodbye to love. The carpenters