Emerson, Lake & Palmer general.
I just listened to Tarkus for the first time today after holding on to that LP for a couple of years now. The titular suite isn't too bad, but I can empathize with some fans pointing to the B side as its weakest link.
Now re-listening to Brain Salad Surgery and while "Karn Evil 9", or anything on that album, is no match for "Tarkus" (Side A) in my opinion, I feel the album is more well-rounded than Tarkus. It's quieter for one thing, the mixing and overall production is better, whereas in Tarkus I felt Emerson's keys were way too overpowering, or they just sound like that through my Polk T15s.