Good animation are always welcome, but some games have ones that are weird as hell, with low framerate, stiff movimentations and sometimes even the lighting changes for the worse. So in that cases, still images would be better.
Can't play games without animation anymore, such immersion breaking. And because of that can't start play Grandma house, but ppl really like this game.
While I appreciate nice animations, I am perfectly happy with still images most of the time. I also really hate animations that look like two dolls getting smashed together by invisible hands, which detracts from immersion rather than adding to it.
If it is about sex scenes, animations always. But if having still images would make updates come faster, I wouldn't mind, specially on games where I play for the story, or for the characters.
The consensus seems to be that animation that's not terrible is almost always prefrable to still images. I agree with that. Bad animation is jarring, no animation is boring, but if the still art is high quality and sexy, I'm down for that, too.
I prefer a good game without animations over an ok game with. Sure they add something to the game, but it's not the most important thing and they need to be done right.