There are a ton of different adaptations of PotO (as seen
here), at least 20 different stage versions of the story exist.
The two biggest name musicals next to the ALW one seem to be
Ken Hill's Phantom of the Opera and
Phantom. I don't actually have the fortune to know much about them but I'd like to try to pry some discussion from the people who actually know about them *cough cough*Fox*cough* so they can further enlighten us.
Someone will to share the soundtracks or how to get them would be super-duper awesome too.