I don't think Pacific Dive has a boat either. We dove with them in 2001 but it was a scooter dive at Airport Beach. Good outfit though. No experience with either of the other two you're asking about. If you're willing to drive to Kihei, B&B and Ed Robinson's are also highly recommended here. Although one of them leaves pretty early, so you have to leave Lahaina around 5:15 to get there in time.
If you catch Lahaina Divers on a good day, they're ok too. They have a big wide boat with all the facilities - nice for coming back from Lanai when the winds are up. Also we had 8 on our trip - and 2 DM's - not sure what they did though as my buddy and I went separate from the group - no problem for them. If they're full though - likely in August - I'd go with one of your other options, they can probably squeeze 24 or more on that boat.
I've done both, so here's my order of preference:
Molokini Backwall - if you've got the experience
Cathedral 1
Cathedral 2
Molokini
Depends on what you're looking for, if it's lots of fishlife/coral, definitely Molokini. Even inside the crater, saw my first(only) Scorpionfish there and some whitetips in under 50'
If it's the wow factor - it's definitely the Cathedrals. Cathedrals is more about the experience of the Cathedral than the fish life. I'm agnostic, but swimming up near the top of Cathedral 1 is the closest I've been to having a religious experience.