(I ask this because, for me, I think the former is much more likely than the latter.)
However, there are a ton of bioinformatics libraries released every year, and almost none of them gain any traction. Nature publications are far more frequent than important new libraries, and you need more political clout to get the library popular than you need to get a Nature paper.
Really, you need to gauge usefulness and interest of your library before you devote a ton of time to it. It's a lot like a startup's product.
Is it more important to get the result, or to use other people's code? Reinventing the wheel is a minor sin compared to not getting results.
The key is to find a modular component that is difficult or novel, and at the same time broadly applicable and hopefully extensible.