Really hard to do a top 5...
College Daze I suggest everyone to play it. I know many people aren't into real porn games, thinking it's lazy, but a lot of work went into this game and the amount and importance of choices is reall great. A lot of replayability.
Timestamps ( and
part 2) Also great. I like it even if there aren't really choices (or at least I'm not sure if they matter). The story is fun and the sex scenes are great.
Photo Hunt A sandbox with a ton of content. There are 2 different routes for some girls and a lot of side events to hunt for.
And 2 classics, they don't need a presentation :
Dreams of Desire (completed)
Being a DIK
There are other games that could be really promising, but they have little content and are updated so rarely I doubt they'll go anywhere, so I'm not mentioning them.