(Almost) everything that feels fresh and unique. That doesn't necessarily mean extreme - even soft play styles can feel fresh. May also just be a physical feature like a long tongue or big clit on a regular non bodybuilder type girl.
Also girls helping me fuck other girls (MFF where one girl is the dominant one, that leads the other girl).
Soft breath play if done right - especially if the girl knows how to do it to herself and her upper chest area and neck show signs of increased blood supply. There was a VR camgirl for a few months that was really good at that.
Increased blood supply in the upper chest area is hot during regular sex too. Especially in the world of porn with all of the faked emotions some real reaction of the body is always nice.
Controlling gag reflex with fingers to turn off mental blockages, especially if a girl has problems to reach that point without methods like that. Regular deep-throat or those wet blowjobs, on the other hand, do nothing for me. If the girl makes intentional loud sounds during the wet blow job it even turns me off.
Although I don't really have a foot fetish (and therefore don't want to lick or smell feet), I like to see her feet during sex. Much better than boots or shoes.
Wet labia sliding along the cock during sex.
An increasingly sweaty body.
Authentic reactions to unexpected events (not the faked stuff shown in "anal surprise" or "facial surprise" videos).
Good eye contact and humor. Communication without (many) words.
