I have been to Maratua a couple of times. It's a bit of a slog to get to. Plenty of turtles, big creatures, and it is famous for a massive (really massive) school of barracuda, at which site the current is pretty ripping. You can stay at the west side, easier to get to Sangalaki (mantas, although I have not had good luck there) and lake Kakaban, which is a freshwater lake that used to have stingless jellyfish in great numbers, but these days they are very much reduced (I would not really recommend it now).
Come to think of it, the massive school of barracuda are not that prevalent anymore either. If you stay at Nabucco, that's more on the east side, very close to the barracuda site, which is the traditional draw at Maratua, where you can go only at specific times based on the tides. There is also a sister resort to Nabucco in the same area, it is newer and a bit further away from the barracuda site,
It's worth going to if you have the time. I remember some really neat rays there (cowtail and blotched).
Bandaneira. Do you know how you will get there? My understanding is that there is no air service and the ferry (from Ambon) is unreliable, schedule wise. But there are a couple of dive operations there. I have not been there, but the last time I was at Ambon, I met a couple who had just come back from a few days there, and they had liked it.
R4 has an amazing mixture of big, small and coral. Fantastic variety. I enjoyed Maratua, but I've been there only twice, whereas I've been to R4 about 5-6 times.
Hope this helps.
