This is something like idea sort of.
This is my opinion just incase y'all get offended or something.

When characters are OP
What I hate in stories/RP's is usually when characters just become too over power or have something over powers, because it usually just makes the characters too predicteble in stories like fights and conflicts or just plain boring.
I mostly like it when characters are like balance in some sort when it comes to them being strong wether they have weakness or not and their strength, powers, and abilities.

Love Relationship
When it comes to characters falling and ships, one thing I hate is when characters meet anotherher character and they instantly fall love or forcefully fall in love, like seriously if you want characters to have good love relationship then don't make them fall in love instantly just make them be friends, aquaintice , or something but don't make them fall in love instantly or force them to fall in love because you want to (like the role-plays). Make characters relationship make sense and not throw in their love relationship making it no sense.

Repetition Plot
I hate when there's always the same plot written because I noticed that usually there's the same plot wether it written sort of differently or not.

Don't try to fit in
I hate when people write something just to fit in with other characters or writer's story is almost as if they just attention or just copying and adding related stuff from other characters/stories just because you feel apart from it.