Well, true polymorph and mass polymorph at least aren’t overpowered for their levels. Comparatively polymorph as commonly interpreted to be a “caster decides” effect, is routinely considered the best 4th level spell overall. It has better single-target save-or-suck disabling ability than banishment, it rival arcane eye in terms of scouting utility, and as emergency temporary healing or a combat buff it outperforms the 6th level Tenser’s transformation.
The only other 4th level spell that even comes close is the “caster decides” interpretation of conjure woodland beings, mostly because you get eight polymorphs for the price of one.