MK9:
Kabal: I absolutely hate characters that reduce a game to mindless button-pressing. Yes, I know there's some strategy involved, but it's mostly just when to cancel the ND and when to let it rip. The biggest key to a successful Kabal is how low you can do your IAGB and how consistently you can nail your ND cancels. That's stuff a machine can do as well as or better than a human. It's purely mechanical, and the risk/reward is almost always in Kabal's favor. He just plain ol' ruined MK9 for me. When Kabal started to get really dominant, I couldn't bring myself to play anymore.
Johnny Cage: Similar to Kabal, but obviously not as bad. Just the whole premise of constant plus-string rushdown (again) boils the game down to who can press buttons better. I want to see mindgames, action/reaction contests, and deep strategy. JC doesn't offer that.
Kung Lao: See above. Lao is ridiculous for all the same reasons. The only thing that makes him slightly less annoying than the first two is that he can't just use the same exact button sequence over and over to win. He has to vary it up between... oh... maybe 3-4 sequences. >_<
IGAU:
Superman: Noticing a pattern here? Superman is every bit as braindead (IMO) as Kabal, he's just not quite as dominant (after several patches) because of the character diversity (and, LBSH, addition of powerful DLCs) in IGAU. F23~breath is just as derpy as ND cancels, and the fact that they gave such a braindead, dominant tool to the posterboy of the franchise tells us exactly what NRS/WB was thinking when they designed the character. They wanted all the kiddies who picked up the game and went straight for Big Blue to feel like they were good at the game. I'm sure it worked. Unfortunately, it translated to competitive play as well.
Doomsday: The only reason I dislike DD a little bit less than I dislike Superman is because he's a more novel character. He's not "SOOPERMAYUN!" Other than that, he's about as derpy. At very high levels of play, he can be slightly interesting, but he should not be as dominant as he is for the skill required to play him.
Scorpion: Same as all the rest--just another derpfest. I'm glad they toned him down, but whether he's top tier or bottom tier, he still takes no more brains or strategy to win than to lose. Just jump and hit buttons and mash out teleport.
I like playing/watching contests of intelligence, strategy, and skill. The above characters offer primarily contests in finger dexterity.