I like a lot of kinds, but the ones consistently tied for my favorite are good ol' oral, and AV, which I like to refer to as Ass Vore, since I don't really like the anal part much.
Getting sat on and sucked up, cute goober just disappearing between those big soft mounds into the fat bottom of a person. The fact that things are supposed to come out of there making it uncertain if the prey will come back out, it gives me a weird impression of permanence if they get sucked into ass. Also the lower body down there is where all the pleasure is felt, which makes it even better.