(I'll keep these brief and to the point so it won't be a whole rant series)
Like
1) Tsubaki- he's not an annoying perfectionist to me, although yes, his stats can be... yeet.
2) Corrin- Yes, he/she can be Mary Sue/Gary stu, but I don't understand how people hate them. Throughout the whole gameplay, I didn't feel any hatred toward them... (not saying they're a good character, but they're not bad.)
3) Xander- I don't even know why people hate him, I didn't have trouble using him on my team either.
Dislike
1) Camilla- oh boy where can I start? She just creeps me out with her dialogues and that... "armor".
2) Tharja- abusive mother and a creepy stalker.
3) Donnel (not totally dislike but)- I don't dislike him as a character, but I had so much trouble just trying to level him up, I just go 'no' to villager units.
I have more explanation and other characters, but I don't have a lot of time so these are the most simplistic version I can come up with.