My feed is very very peaceful generally as a result of my blocking criteria that allows me to curate my feed. I don't fight with people, I don't argue, I just block and move on with my day. 10 stars, would recommend. It's how the block is meant to function here. Almost no one uses the FYP. Your feed is meant to be who you're following, and so it's up to you to manage what you see accordingly.
So, aside from all the usuals (Trolls: blocked, bigots: blocked, etc), as a fandom blog a lot of that criteria revolves around just basic fandom etiquette for me because that's how I like to function in fandom.
Are they being hateful towards the fandom? Blocked. Nuance in that polite disagreement is fine, but if we're launching insults over what amounts to ship disagreements or not liking a character that someone else likes, they get a block. Especially if they're using ship or character tags just to get their rant seen. I don't like when people are dicks about this stuff in a shared space. This is also why you generally don't see me discussing ships or characters I hate - I'm here to water my garden, not shit in someone else's yard. So don't shit in mine.
People bullying others in the fandom or anywhere else: blocked.
Body shaming actors: blocked.
If someone is continuously posting some opinion that really drives me crazy and it's not tagged in a way where I can use the tag filters: blocked. Not because I hate them or anything, but just because I curate my feed with stuff I enjoy (I'd love for tumblr to give us an option to just hide someone's posts from our feeds while they can still see ours, but alas).
Having a fic or post and tagging every character an actor has played when the post/fic is only about only one of those characters: blocked
AI users: instant block if admitted or if I'm super sure. There's still a few on my feed and in my fandom I'm reasonably certain are using it but I'm holding off for now because I'm looking for a little more evidence.
Anyone putting out very extreme trigger-y fics or fantasies without tagging it: blocked. Not because I don't think they should be able to write it - I'm very anti censorship - but because if they won't use the tags that allow me to hide it, then I'm going to essentially do it for them by blocking.
My blocklist is very long and I don't remember 90% of them cause I pretty much just think 'oh you're being an ass, blocked' and then forget about them, but I'm delighted to say nine times of ten if I open the comments of a post with some drama in the comments, I just get a whole lot of 'this comment is hidden because you have blocked the user'. And oooooh how lovely that is. Guard your peace, babes. Follow people you enjoy hearing from, block whoever makes you miserable. You will be so much happier.