You are right that at first, consider if an ICO has a working product. If you want some ICO's with working product I will name two but I don't expect you to like it because for some this two might be bad. First is shadowtoken ICO. They already have a working game where the tokens will be used. Also, there is opus with an already working music streaming platform. Some ICO's are good too even if they have a working product, just be sure it has a good team and also a nice concept.