Ramsay Bolton was also an incredible heel, although he wasn't nearly as hatable as Joffrey because Joffrey also established himself as a sniveling crybaby so he really had no redeeming features.
Ramsay also has an odd sort of coolness to him. Like, he's clearly crazy, but he's also a bit snarky, and like you implied, he DOES get shit done. So while he's way more squicky in some ways, he's also more likeable in an odd, twisted sort of way.
Sure, you're still rooting for someone to shove three feet of steel directly into his face, but I don't think you get that same universally visceral YES! moment with him the way you do with Little King Shitheel.
Joffrey was more sympathetic than Ramsay Bolton. I felt a tiny bit bad for Joffrey because there was never any way he was going to get out of Tywin's shadow, even if he was a good person. Also unlike Ramsay, Joffrey never targeted his family members for execution. His biggest act, killing Ned Stark, was impulsive and cruel but basically where the Lannisters were going with Ned anyway.
Joffrey very likely would have killed some of his relatives eventually. He hated Tyrion, bullied Tommen, etc. Keep in mind that he threatened to rape Aunt Sansa. How long do you think it'd before he killed her? The difference between Ramsay and Joffrey is that Joffrey died before he do even more heinous things. ---