In terms of top tier fights relative to floor, I think P3S, P5S, and P10S take the cake here. I think P12S P1 is one of the more fun phase 1 execution-heavy two part fights, whereas I think P4S phase 2 is actually the best second phase. But second phase, I'm probably a little biased because Curtain Call is just significantly better than Dominion and Gaiochos 2 as far as soft-enrage damage mechanics go.
Anabaseios probably had the most even spread of enjoyable fights, with P9S being a slightly worse P5S (which is fine, because P5S is great), and P10S being just the best second floor fight this whole tier. P11S is worse than P3S by a longshot, but it's not a bad fight - it's just an overly safe, comfy design. P12S is fun even if I think phase 2 is largely just a remix of P8S phase 2.