We visited both but some years ago, 2004
Yap has a lot to offer and in the right conditions some awesome viz.
As has been mentioned Yaps primary draw is the resident mantas.
Goofnuw channel is a great dive site to see them, strong current but once you get in behind the cleaning station just sit back and watch them glide in. 9 mantas on one dive is jaw dropping. Get the right time of year and you can see many more.
It's not guaranteed but you've got an extremely high chance of seeing them, they move around the island with the seasons.
Yap caverns also a great site, lots of long swim through caves with sun light breaking through in many places giving some great photo ops.
Very good Macro in Yap, beautiful critters.
some dedicated shark dives, often with Tigers
Mandarin fish dive right next to the hotel.
We didn't dive any wrecks I'm not sure that there are any to see in Yap.
We stayed at the Manta Ray bay hotel run by Bill Acker they had their own micro brewery (Manta Gold not to be missed)
Great atmosphere, very laid back. Lots of cultural activities to do as well (stone money)
An almost boutique dive experience, the largest number of divers we had on the boat was 6 and only for two days.
Palau does have a greater diversity of coral and of course jelly fish lake which is unique.
Diviing was based on the boat consensus, we typically had 6-8 divers on the boat every day.
Some repetitive sites, but at the same time they were world class sites.
I'd second the recommendations above regarding Liveaboards.
We were shore based, the feedback from talking to others there was that the Liveaboards visited some of the more remote sites and were excellent.
Both locations have some great wall dives and great macro opportunities.
In short I'd say if you want mantas head to Yap, if you want amazing lush wall dives with great vistas of coral, Palau.
What a great dilemna to have, I'm slightly envious.
Whatever you decide have a great trip!
Edited by sharkbaitdiver, 23 June 2013 - 03:34 AM.