Rock Candy makes some neat stuff. Not only are the animations nice, he puts a lot of neat little details too, such as the belly growing bigger as more cum is pumped in, or orifices gaping the more they're used. His more recent games also have a lot o customization options. You can check some samples
here if you'd like.
And you can check
this post for a list of makers and some of their games that pretty much all have really nice animations. They're japanese, but a lot of them have translations. They play like visual novels: lots of dialog, you can make some choices every now and then, and every so often you get the animations. If you want to sample the goods, you can find the animations pretty easy on image boards and such.