Unending BE is my favorite, even if it's a nightmare to navigate. There is one story arch I prefer there above all the others I've seen. It's the one with the Alicia and the Automorph.
http://www.bearchive.com/~addventure...020/20000.html
It starts here, with the last option, and progresses in good ways along almost every single route thereafter.
There's one more I saw brought up recently; Furventure.
http://www.furventure.com/index.php
It's odd... some stuff just looks like regular furry, others like it was taken straight from Belial.