Pervader is criminally underrated. It's got some of the best art among furry VNs, for both sprites and backgrounds (though I'll admit the amount of expressions per character is a little limited), great writing, and it's doing something different, which is always a plus.
One thing I really appreciate about is that it truly feels like a game written for adults, it doesn't really ask you to self insert into a barely above 18 character that has his life ahead of him and hasn't figured himself out yet. Which is a somewhat of a rarity, unfortunately.