I'd have to say that currently Y is considered a "brand" now with Mike constantly mentioning the companies on his blog, Y with a strong community, and PG was the first to introduce this concept.
However,if an entrepreneur had the honor of being accepted into either Techstars or Y Combinator, I'm sure he/she would work their butt off not only for themselves but to represent the program he/she is in. Multiple players foster a very healthy competition.
We'll just have to wait and see which program selects the better "animal" entrepreneurs for this round. The success of a startup involves not only the people heading it, but a large part depends on the entrepreneur themselves and the ability to implement or create something useful. How very exciting!