Which villain of the three would you say is better?
Frieza has no depth whatsoever and gets random power-ups later on....Aizen is way better.
Neither does Aizen, the dude is just a sociopath with a god complex. He's not interesting in any way. Neither of them are MEANT to have any depth, they're not meant to be relatable of sympathetic. They are both pure evil, by Kubo's own admission in Aizen's case mind you.
Trying to say I don't understand character writing while evidently not understanding not every villain needs to be deep. Sympathetic/Relatable antagonists and irredeemable/pure evil villains are both perfectly viable approaches and whichever is better depends on the execution and personal tastes.
So yeah, I'm gonna go with the guy who headlined Dragon Ball's best saga over the guy who carried one of Bleach's worst arcs straight into the ground every damn time.