As far as how the diving rates here..
I've never been to Palau, so I can't comment on that.
Yap: Yap is good as well, but different. I can't say it's better or worse. We have Mantas here but not in the numbers they do at Yap. I've also seen some pretty spectacular things here that I hadn't in Yap. We don't have as many Crown of Thorns stars as Yap does, in fact it's rare that I see them and I have yet to see a Lion fish here.
Chuuk was fantastic in its own right. A lot more fish than here and the soft corals on the wrecks were more abundant than I'd ever seen here. Although, I found a spot last weekend that had exploded in soft corals where the year prior there was nothing.
If you check out my flickr link on my profile, you can get a pretty good idea of what's to be seen here.
Good and bad...
Good: The diving, fishing and surfing here is top notch.
Bad: There is only one place that really does diving and only one that does surfing.
Best thing to do is get hooked up with a local diver. We have a few options for diving and there are a couple guys here who rent out tanks (67, 80 and sometimes 100cuft).
Average tank rental is $8-12 and the boat is $60 for the day, plus gas. We split the cost and do 4 divers per boat usually so we're not packed in like sardines.
This is a local thing, so you don't have fancy boats or divemasters.
If you want something more formal, the Village does a great job. They have very experienced divemasters and a 2-tank dive will run you about $90 plus lunch.
Another local operation here that is not well-known is the Dive Locker. He charges $75 for two tanks (67 cuft) and it includes lunch and beverages. All of his kids are certified divemasters and his wife will make you whatever you like for lunch. Normally during our surface interval we'll trawl for tuna and have fresh sashimi along with whatever we bring for lunch. If you're into shellfish we can grab a giant clam or two as well.
Both operations are good. The Village is great if you're staying there as they provide a full package. Most of the local expats here will use a local guy to take them out if they're experienced divers and our group usually has at least one rescue diver and/or an instructor along for the ride.
Hope that helps...
If you're in Yap, I wouldn't dive with anyone else but Manta Ray Bay. I like their style and it doesn't feel like diving at a resort where you're held to strict rules and feel like you're in a cattle car. It felt like I was out diving with my buddies.
If you do get to Pohnpei, make sure you get to Ahnd (Ant) Atoll. It's the perfect example of a picture perfect dive experience. Village charges $130 per person for 2 tanks and it's more than worth it. You can see the photos in my flickr profile.
