Really the best solution for this is to provide as many options as possible. You should develop your authentication services in a way that allows OAuth to be us

Really the best solution for this is to provide as many options as possible. You should develop your authentication services in a way that allows OAuth to be used just as easily as a "custom login". In addition to that, anyone who says that having "your own" login isnot worth the time to develop it is just plain silly. It takes almost no time to develop and anyone who has been in the web business for longer than 1 website knows this. As a startup I want to make sure that I am not alienating any user from my service. On that note, It is important to realize that certain sites or services on the web require some sort of social graph integration that require a login with a social networking account. In cases like this, you are developing an app for a user base that is not on FB or Twitter and then (purposely) alienating the rest.