The answer mainly depends on lighting/water quality. In blue water, it really doesn't matter. In lake or green water where light levels fade fast, you'll probably want something more recent as the newer models have better low light capability. One item you do need to factor in is that the older models (Hero HD and HD2) with the domed housing require a special flat glazed dive housing to focus. These are expensive and hard to come by and may push the overall cost above the cost of a Hero3 in its regular, dive capable housing. As far as the Hero3 models, the Hero3 Black was the only real Hero3 model. The Hero3 Silver is nothing more than a rehoused Hero2 (HD2) and the Hero3 White is just a rehoused Hero HD, both of which had same limitations regarding low light situations that their predecessor had. Ultimately, it all comes down to your needs. Personally, I wouldn't go lower that a Hero3 Silver. But then again, do you really need a real GoPro as new clones are half the price of used GoPros and if image quality doesn't matter, that may be the more cost effective route.