Shorts above the knee. The others reveal a bit too much or they just make terrible tan lines.
Surf shorts are the best or even long shorts, but please please, never never even think of wearing those diving swimmers wear at olimpics. They're ugly and old fashion, even if you have a great body and a big pack. Believe me you'll look sexier in surfing shorts with a good body. If you're gonna wear those speedos or worst a thong, I'd rather see you naked.