Others don't like that I like:
Corrin: I really never had a problem with them, and while I respect the opinions of those who don't like them because they considered them a bland character, I can't help but find it ridiculous that people blame Corrin for the Fates' poor story instead of oh, I don't know, the writers?! And it's not like Corrin was the only one to be negatively impacted character-wise outside of support conversations. Almost every main character, Azura and Xander being two of the worst offenders, suffered to some degree under the narrative. Overall, while I would have liked Corrin to have been more developed, I still don't mind them as much as other people do.
Jakob: I'm not entirely sure whether this one counts, because I hear how popular he is and then I see a lot of people dumping on him. Honestly, I really can't see what the problem is with him. Yes, he's a dick, but he's an entertaining dick (Think Romano from Hetalia), and he actually is capable of showing respect to other people, in his own way, of course, which I thought made him more three-dimensional.
Clive: Seriously, people hate this guy? He's probably one of the most consistently likeable characters I've ever seen in a Fire Emblem game, not to mention how much of an excellent front liner he's been in my play-through so far.
Others like that I don't like:
Ephraim: I don't get why people like him so much. I really don't. He's not developed, whether he has flaws is more debatable than it should be, and his route is nothing but a glorified power trip. And what's worst of all is that you can completely avoid his route and not miss anything. All this, for me, culminates in a character who's put on a pedestal for no valid reason and is pointless for understanding the game's plot.
Ryoma: He's a good unit... That's the only positive thing I'll say about him. Ryoma, to me, epitomizes everything I hate about how Hoshido is framed: he comes off as perfect, but once you stick around, you see how self-righteous and narrow-minded he really is. Needless to say, it has driven me up the wall far too many times. I think the one thing that pushed him into hate territory for me was his actions in Chapter 12 of Conquest.
Python: I don't mind his personality, but God he sucks as an archer. Almost every time I've used him he ends up dying, and it's a shame because I actually wanted to like him.