A lot of guys swear by the O'neill psychofreak, O'neill's top of the line wetsuit and I can see why. I got one last year and it's far warmer than my old steamer by a long shot, and super flexible. I kite up to 5 C air, 5 C water. but only for a few hours max.
The psychofreak is made for surfing not wind sports so it doesn't have that smooth skin, but I'm not covinced you need the smooth skin. My old suit did have smooth skin and I was far colder in it, one reason I believe was that its did not allow the water to get into the suit, and you need the water in the suit to warm up then keep you warm.
Patagonia is suppose to have a very good wetsuit too, but I never seen anyone with one.
Both suits are expensive, but you get what you pay for. and when it's cold you better pay the extra couple of bucks if you want to have fun.