I used to absolutely hate Superman, but now that I've been exposed to him more I still hate him just slightly less. I honestly cannot understand his appeal and I find him so insanely boring that he would only be interesting as an antagonist or villain, such as in Dark Knight Returns. Only in those situations is he memorable as he now functions as an obnoxious idealistic being with god-like power, making him perfect as a final boss. I trust I'll like him in this story as well for similar reasons.
After Young Justice I've grown to appreciate characters I wouldn't give a damn for or possibly even know about otherwise. Characters like Captain Marvel, Blue Beetle, Red Arrow and the like. Damn shame that show's getting canceled, especially right after they put my boy 'Stroke in there.
I used to greatly dislike (not quite on a "hate" level) Superman for a long time. "Ooh, look at me. I have new powers as the plot demands and the only people who give me any trouble are petty criminals who just happen to acquire green rocks that are my only weakness." In short, I viewed him as a Boring Invincible Superhero. That is, until about a year ago when I stumbled across a certain clip on Youtube. Specifically, Superman's fight with Doomsday in Justice League Unlimited. "Wait, Superman has actual THREATS to deal with?" Realizing that the Man of Steel had worthwhile adversaries caused me to investigate deeper into his mythos, and before long I grew to like him. Within about a month, I effectively became a Marvel-to-DC convert, learning that there are indeed interesting DC characters besides Batman.
Superman and The Flash. Superman I always thought was the original Gary Stu until I started picking up comics and reading them (and seeing he actually is a pretty likeable guy, more so than Batman) and I never liked Flash's powers (super speed = meh) but I do like the guy's personality.
Aquaman, Black Canary, Hawkgirl, Martian Manhunter, Circe and Poison Ivy for Injustice: Gods Among Us Wanted- Injustice: Gods Among Us, Fire Emblem Awakening
Cyborg. I really hated him for the longest time. I hated him in the Teen Titans show, but when I read New 52 JL I began to feel bad for him. I still won't say i'm a big fan of his, but I went from hatred to thinking hes a pretty cool guy.
Believe it or not, when I was very young I found Batman to be absolutely boring. I thought it made him lame somehow that he didn't have any powers, and for a long while I preferred Robin because he was closer to my age at the time and I thought he was cool somehow, like being able to kick tons of ass while being just a kid.
I still think Robin is awesome, but now Batman is bar none my favorite superhero tied evenly with Spider-Man. There's so many reasons why I'm so deeply fascinated with him that I could take forever ranting a laundry list about him, but some of the biggest ones that immediately come to mind is that (in my opinion) he's a great example on the constructive use of individuality and dark emotions, why the law is often inadequate to truly punish evil and deliver justice while still being righteous, and the limitless human potential we all could aspire to.
I just find it humorously ironic that I used to be unable to stand Batman, and now I couldn't be a bigger fan of him.