I set up a trip last year, and was deciding between Palau, Maldives, and PNG. I ended up going to Palau and had a great time on the Ocean Hunter I. The info I got was that Palau had more varied diving, with wrecks, reefs, walls, caverns, and verge-of-deep-blue spots like the Blue Corner in the mix. I can't compare the Agressor boats for the two locations, nor can I even compare the two destinations from experience, but I can say that I had an utterly fantastic week of lots of different styles of dive sites in Palau. I'm also keen to go to someplace like Raja Ampat, but I must save some more wampum first. (In the meantime I'm squeezing in 4 days in the Philippines in October as part of a work trip).