It depends on if the ideal candidate is the sort of person who wants to work with people who wear tee shirts that proclaim themselves the best programmers to the point that they will wear such a tee shirt.

To me, worrying over which clever slogan to put on tee shirt is a way of pretending to do the hard work of recruiting which is talking to people and evaluating their ability and deciding it doesn't fit and telling them so and being humane while doing so.

I think, "StartupName: We are hiring" is more to the point and a better conversation starter.

Good luck.