I'm asking the same question at the moment. I've heard that diamondlite is the best material, but I don't know if that is true. It apparently rates zero on toxicity, is non-reactive and non-cytotoxic.
I'm not happy with white composite fillings because they might contain Bisphenol A which leaks estrogen into the body and concerns have been raised that it can contribute to male infertility or prostate/breast cancer.
I don't want another metal either.