There was a post earlier about the art of tattoo all over the skin, to cosplay vampire. It's really cost a lot of patience, creativity and brave to do that. Compared with tattoo, body paint is much more tender way to do art, although it still takes a lot of time and design, we have more freedom at how long we wanna keep them :)
If to realize the second skin by zentai suits, it can't look so realistic as the skin paint, but to do zentai, it's quicker and easy to repeat use. However, the zentai outfits' camouflage is rather limited, by the creative cloths you could find. For body paint, you could almost do anything you like.
The thing suitable for me is zentai, as I am lazy, very lazy, and I am lack of the art talent too.