Well, for starters:
I’m also not a fan of ROs who are obnoxiously pushy (Arden Devereaux) or domineering (Ava du Mortaine (might’ve misspelled that)) with the MC.
Snarky, sarcastic jokester ROs tend to think they’re far more hilarious than they actually are (Rylen Villenueva, Farah, one of the custom personalities you can set for the royal in Odessa Dating Games). I should note here that I don’t hate sarcastic or jokester characters, but that comes with the obvious caveat that they have to be done well. Sarcasm for sarcasm’s sake and “zany” humor which seems to not know what “zany” means doesn’t cut it for me.
I have never cared, and likely will never care, for villain ROs (Manerkol, Mornie (even though she kinda sorta doesn’t count), Saffron De Lisle, that evil queen with the machine army from that one CoG story I keep forgetting the name of).
On a related note to me repeatedly not knowing the evil queen’s name:
At least I can remember the other names in this list. I hated them, but cared enough to hate them.
Enemies/Rivals-to-Lovers is easily one of my least favorite tropes in existence, particularly in the case of the rival, if said rival is written to be a thoroughly exhausting person to be around (Blane Rekner, Sebastian Lopez de la Rua. Rare exception goes to Alex Hayward of Vampire’s Kiss, who I was an enemy of completely by accident, and also developed a romance with completely by accident).
If an RO is written to be antagonistic to the Nth degree, and for whatever reason, the narration swears up and down that I’m supposed to be madly head over heels for them (Seven Lawless), odds are good that I will shut down their romance path immediately, first chance I get; or, if outright blocking an RO isn’t an option in that story, I’ll go out of my way to be as disinterested in them as possible out of spite.
Arrogant ROs who think they’re the greatest thing on two legs occupy zero percent of my attention (Antonia Barlow).
New to the list of personalities I hate, courtesy of Merry Crisis, are spineless asshole ROs (Lin Qiu, your high school sweetheart-turned-ex whose overbearing snob of a mother pushes her into dumping you, then Qiu tries to lay the blame for the relationship falling apart at your feet, then has the gall, eight years later, to assume that you’ll just take her back after complete and utter radio silence following your graduation).
I could probably go on, but I think I’ll stop for now. I’ve painted a relatively clear picture of where I stand, I think.
(Oh yeah, special mention goes to ROs who are touted as belonging to a certain personality type, but turn out to not even slightly represent that personality - like a “stoic” RO who turns out to be an enormously whiny bitch, for example.)