They both have their advantages. I will list 4 major advantages of each, there may be more but this is the short version.
|Backbone||September 2010||May 2012|
|Ember.js||November 2011||April 2013|
|AngularJs||March 2012||August 2014|
It is hard to compare three great evolving libraries. They all grow and change, but it is good to know what is working now and what isn't.
This library probably is evolving faster than ThreeJS. It is always hard to tell, but they both don't have that many contributors besides their founders. It does look like Babylon had more updates recently and s more active community.
A-Frame tutorials use "document.querySelector"; however, using document.querySelectorAll, has a bug that doesn't apply. Also if you want to affect newly added objects, querySelector was having issues (Edit: It is working now).
Luckily, we have a workaround to use jQuery.