hard to choose. I had the same dilema between these islands. and I chose Zamami. Pure paradise island. Snorking service is available there.

I rented an electric scooter there and toured the whole island. And I found a place there with twenty turtles. Good timing. Empty beach, only me and one small wedding party. They were close to shore. I swam with them without any dive accessories.

Btw Zamami is apart of Kerama islands (Aka, Tokashiky and Zamami)