I think competition is good. Soon after babilon.js got released I took a look at their file format and did a loader for three.js. This made me see how much three.js needed some geometry structure refactoring (moving towards a bunch of flat typearrays). I'm slowly working on that but I still need to find a nice API for it [1].

[1] https://github.com/mrdoob/three.js/issues/3672