My experience in Rhodes was good. Its pretty populated at the northern end but the wind was best on the western side I think. Mostly onshore and stronger than the east coast. There were lots of options for rental along the coast. I never went to Prasonia as its a bit of a hike and I was based at the other end of the island. Most of those islands seem to have some pretty nice conditions and usually I could find someone to hire me some gear with out to much notice. It was great to island hop on the ferries and sail in a variety of spots.
From the web.
kiteandsurfrhodes.com/en/windsurfing-rhodes/trianda-ialyssos/