From my research prior to the trip, the Arch. Adven. and Seven Seas were a little more upscale boats which would be very nice. Pindito is also well recommended. Ondina appears good but not as "luxurious". I agree that the boats did seem to book up pretty quick.
We saw two other boats, the Ocean Rover and another phinisi type boat, while on the trip but only the Rover dove in the same area on one dive, though I never saw them underwater. We were anchored well away from them.
Incidentally, hot water is going to be a little challenging in that part of the world, though certainly possible. The Paradise had plenty of hot water, in fact too hot if not careful, and the bathroom was the size of most of my previous entire cabins not including the bed. However, the hotel in Sorong was nice but used little individual heaters in the shower. With the big showerhead dumping water, it was easy to use all that hot water up quick. Step outside the aircon though and you had all the "hot" you could stand.
