Strange, my opinions differ a lot here. I quite enjoy the Rape, Tentacle and NTR content (although it all stays within fantasy realm, I wouldn't do such things IRL).
Pregnancy related content is a no no though, along with Furry (I enjoy cat girls, as in girls with tails and ears etc, but full on Furry... *cringe*).
Furry, vore, scat, watersports, vomit, enemas, diapers, primal bestiality (IE: dog is not ok, monstergirl is ok - it has to look relatively human and be capable of higher intelligence), necrophilia, pregnancy, senior citizens, some incest (cousin and siblings is ok, everything else is not), bakunyū, foot fetishism/footjobs, small penis, menstrual, milking, bukkake, cum swapping, felching, fisting, and self-fellating.
I dislike rape, anything with more than 1 guy, extreme guro and scat(WHO GETS TURNED ON BY POOP, HONESTLY!?), Yaoi, and any loli that has actual kids in it. Other than that, ill read pretty much anything.
Guro
NTR that starts Vanilla(I can't stand it. I like NTR and all, but it's just a waste when it turns NTR when it starts Vanilla)
Group NTR(It's pretty bad in my opinion)
Preggo
I'm not a fan of yaoi, though I do like futa-on-futa and futa-on-girl.
I'm okay with minimum guro. Likewise some level of guilty pleasure with NTR, mindbreak, rape, though that's a thin line to easily cross to not like. Mostly depends on how good the art is.
Oh, I don't find scat that weird, unless it happens during/after sex or it's too excessive (like there's piles of it everywhere for some reason). Not a fan of eating shit or water-works/golden showers either.
I generally don't like NTR but I'll fap to it if the boobs align just right.
I however can't stomach guro, as far as scat goes, I don;t like it but if it's minimal I can keep trucking.