There are plenty of great AVN's out there that get regular work, but sadly yeah, it's an all too common issue in this scene. Vaporware is real, and it can be painful. I've had quite a few stories I was seriously invested in that either dropped off the map completely or were cancelled.
A really great on that I have followed closely up until recently(1yr between updates is a bit much for me, but some people are patient) is Eternum. REALLY great story, amazing visuals. Highly recommend if you're patient enough to wait a year between updates
Leap of Faith is another really great one if you're into heavier stories(has some pretty heavy tones, but it's a great story) and best of all, it's complete.
you can check out my profile to see some of the one's I've played and supported on here.