Depending on the sailors weight I think windsurfing and kitesurfing both have their strong points.
As a 100kg + windsurfer I needed a lot of wind to get up on a plane, or a sail that was really large. I imagine a kite would have powered me up earlier and been easier to manage.

I sold my sailboard kit 5 years ago. If I was to go back, I would probably go for a kite.