That depends on how you define "hate". If you mean hate in the sense of actually just outright wishing a character didn't exist, I can't really say I feel that way about any character. If you mean it in a lore sense of "This is a character you are meant to hate", I'd probably ironically pick Infinite. Not actually because he's meant to be an unlikable bad guy, but because he's so poorly written that it's hard to even take him seriously. The only way I could ever support him returning in a future title is if they find a way to make him work.
Primarily, I think the biggest problem I have with Infinite is that he comes off as the character equivalent of a kid that think's they are the best at a PvP game raging and resorting to cheats/hacks to prove they are the strongest when they start losing to a better player. Rather than Infinite earning his power through truly impressive and intimidating feats, he is handed his power through no effort of his own by Eggman giving him a new plot device gem that happens to be stronger than the Chaos Emeralds because plot convenience.
Worse, even though he's hyped up as the strongest enemy Sonic has ever faced early on, he's made into a joke immediately after. It ends up feeling more like they wanted to hype up Sonic getting a huge power boost through minimal effort than to actually write a compelling villain. I'd even argue it's worse than when Sonic beat Perfect Chaos in Generations while in his base form, because at least then the implication was that Sonic has grown that much since Adventure. Infinite is a plot device to make Sonic grow tremendously within the timespan of a single game, and it doesn't feel natural or earned at all. Sonic never even has to struggle, he's just immediately superior when they have their rematch for no apparent reason. No training session or anything.
