I tried Ember some time ago and it just didn't click for me. It's hard to explain exactly why, but I found myself switching between too many files to get simple things done. I've done some simple Angular work recently, and found it a relatively simple system.
In defence of Ember everything about the project -- docs, community -- seems to be better organised than Angular. The Angular docs are hilariously bad.
I know, it's a terrible, horrible practice, but hear me out.
Learning Ember, especially at the beginning, required me to sort of rewire my brain about what goes where. It's "MVC", but the M, V, and C mean totally different things than they mean in Rails. Really it's more like MVCRT (model view controller route template).
I found all the different files extremely confusing at first, especially since each tutorial told you to lay things out slightly differently.
If you put it all in one file though, you can really easily move stuff around. You'll find yourself frequently pulling stuff out of a controller and sticking it in a view, or a route. Having to constantly switch files, remember where things are, create new files, and remove stuff from version control really puts a damper on things.
My advice to anyone starting with Ember: download the starter kit from emberjs.com and try to stick inside that as long as you can. You can just drop it into your Rails /public folder and get up and running.
Once you have a solid understanding of the architecture, and your app is getting bigger, it's literally an hour's work to pull everything out into separate files and drop it into something like the Rails asset system.
http://github.com/stefanpenner/ember-app-kit aims to prevent and mitigate the tooling pain, by having the community bear the burden.
I don't get why people keep on saying AngularJS doc is bad.
Maybe I'm weird but I've found Ember JS to be horrible and AngularJS to be very good.
I was more hoping those that have a strong opinion on one or the other would ensure that they try them both first.
In the case at hand, spending half a day each (or even more) with angular and ember is not enough time to gain a truly informed opinion of either. These are big frameworks with many features, and each harbors both gotchas and benefits that won't emerge until you've worked with them over time in real projects.
For developers with limited time, asking advice from fellow trusted developers is not only acceptable, but also, in many cases, the clearly optimal strategy. Of course, the trick is to find experienced people to ask with tastes and values similar to your own.