Oh god, too many canons to name that I love playing against. I'll name out a few that my partners probably can guess already who I'm obsessed with their portrayals of.
I never thought I'd be so into one of my partners take on Cloud Strife from FF7- granted I just finished playing the Remake and I disagree with people who think he has no personality- he's just a socially-awkward introvert. Though our story isn't focusing on his characterization that much- my partner is able to write him in such a way it feels really heart-warming to see him come out of his shell and express his love for the one he's fallen for (in this case Tifa!)
Another one is my partner's take on Ezreal from League of Legends, I've sung him praises for a while but it has to be said that he does a fan-fucking-phenomenal job at making this character just utterly adorable and sweet- despite otherwise being a rather carefree and rambunctious sort of person. I have an utter weakness for the explorer type of character that Ezreal fits the bill of and I honestly can't think of a better character I've gotten the pleasure to write against so far, it's just so satisfying having a character like that really want to devote himself entirely to someone in a similar situation- craving love and affection but never getting it. Finally, they get it with each-other and it's just a beautiful explosion.
But in general, I tend to be really into the sort of dopey but well-meaning sort of guy that always gives his 110% percent in everything. Think like Caspar from FE3H or Lloyd Irving from ToS, that's my ideal 'type' I love to play against I suppose. While broken characters are fun, I usually prefer to lean into people discovering themselves- realizing how truly lonely or how much want they really needed when MC comes into the mix- the feeling is usually always mutual. All in all, I like sweetness and characters I think that can deliver that sort of beautiful and passionate romance I'm literally obsessed with writing!