The only truely natural, effective sunscreen is zinc oxide. It is natural, broad spectrum, free of nasties, and ideal for sensitive skin. But the downside is that it's a bit more difficult to apply and can leave a white film on the skin. DS has terribly sensitive skin, but zinc based sunscreens are fine, even on his face. At the moment I'm trying a sample of Megan Gale's Invisible Zinc. It's far from invisible (at least the Junior one I have is, the regular Face and Body one might be better), but it is otherwise good. It makes you waterproof too
It's not as greasy as UV Natural and Soleo either.
I think Natural Instinct have just released one as well, but they don't seem to have testers around yet, and I hate paying a fortune for this sort of stuff if I can't at least check the texture first.