Joker is awful because his villainy has no legitimacy. Someone wouldve killed him by now. Cops, guards, other inmates, some government hired mercs or soldiers, other heroes or other villains. At the very least guys like Penguin or Two-Face have businesses and try to avoid scrutiny or added pressure. Jokers elevated insanity and terrorism existing just makes no sense. He cant buy anyone off or endear people to his cause because its just chaos and murder for the sake of it.
Frieza at least has the power to resist his enemies and stand by his throne. And seems to mostly be training to surpass the gods if thats possible. And he was only a villain in his debut arc, since that he remained dead, revived for a day in some movie and dead again until the TOP.