Pranburi is nice, but with all due respect, it is a stretch to call Hua Hin "crowded". I just came back from three weeks in Hua Hin, and the maximum number of kites I counted on the water was 40, and that was when the first wind hit after a two-day spell of no wind and everyone was desperate to get out on the water. On most afternoons, the average number of kiters on the water was about 20 - and that is on a beach that is several kilometers long...
As in many other places, there is a tendency for a "swarm" of kiters to congregate outside one particular small stretch of the beach. Why, I don't know - perhaps to show off? If you start from any other place along the beach, or simply ride downwind/upwind for a couple of minutes, you will have plenty of space on the water. I usually prefer to keep several hundred meters between me and the next kiteboarder, and in Hua Hin this is not difficult at all.
Boracay or Tarifa or Cabarete - those are places which you could describe as "crowded" in the true sense of the word. But Hua Hin? Plenty of space on both the beach and the water there...
Anyhow, to get back on topic, I think both Pranburi and Hua Hin would work for a beginner.