It depends what you are looking for. If a good beach is important you can't go far wrong. Your son is likely to love the sea, there are usually big rollers, but its still pretty safe. Great fun with a belly board!
We holidayed in Dalyan with teenagers around the same age as your son a few years ago and they loved it. It's the sort of place where they can have a bit of a freedom, but it's safe enough for you to feel comfortable with it.