The only thing that matters wrt software libraries is if it helps deliver and maintain software more efficiently and with less frustration than others. There ar

The only thing that matters wrt software libraries is if it helps deliver and maintain software more efficiently and with less frustration than others. There are three dimensions to this, how great is the library today (with regards to efficiency of construction and maintainability of software), how much better (or worse) will it get in the future, and how long will it be around. Unfortunately these things are hard to measure and predict. The number of committers only gives you some insight to any three of these things, and can actually mislead you. The Javascript ecosystem is ridiculously fast moving (which is a nice way to put it :)) so number of committers doesn't tell me if all those folks will just jump onto the next thing that comes along. Also, the Javascript community has developers of a wide variety of skill levels, so the number of committers doesn't necessarily say much about the quality of the library without understanding who these committers are. I'd argue there is often a small number of key contributors to any open source project, with other folks contributing small patches to fix bugs or minor enhancements, so the total number of committers doesn't tell you a much more important thing: who are the key contributors, what is their background and views on software engineering, and how likely are they to remain committed to the project over the long term? It seems to me the main thing Angular has going for it is that Google has bought in to it, so that means no matter how flawed it is (or not), it's not going anywhere anytime soon so you can be sure security fixes and bugs will continue be addressed over the long term. Then again, Facebook seems all-in on React (and I'm not sure about Ember) so maybe this isn't much of a differentiator.