I wouldn't try to open new altcoin. What I will do is not be greedy and try to help the development of some altcoin that I think is worth puting my energy and time in. It is hard to start from scratch and there are already to many altcoins out there. If we say that I "invent" another protocol that no alt uses right now guess then I'll opt for making my own, but as long as my imagination have some well known features well most likely will try to participate in development of an existing one.