Well our pick comes with a big disclaimer, we chose Polymer. I am not sure if it's already a good idea to build a big consumer-facing using this tech as it's very future (modern browser) oriented.
That said, Polymer has been absolutely awesome to work with. Even though it's not so much a framework as it is an interface/wrapper around some cool new stuff that's in HTML5 we built a very light weight framework around it and that has been a great experience for us.
It's possible we did some more work than we would have to on other frameworks, but we got a lot of control back for it. I think we would've went with something light like backbone.js otherwise. And it's also possible that it would not have been a good choice if we had team members with less experience (i.e. every now again there's some advanced fire extuingishing going on).
Anyway, our audience is a low-traffic tech niche and our app is a SPA that's mostly read-only, so that's a very small target that gives us a lot of room for taking chances and picking tech.
That said, Polymer has been absolutely awesome to work with. Even though it's not so much a framework as it is an interface/wrapper around some cool new stuff that's in HTML5 we built a very light weight framework around it and that has been a great experience for us.
It's possible we did some more work than we would have to on other frameworks, but we got a lot of control back for it. I think we would've went with something light like backbone.js otherwise. And it's also possible that it would not have been a good choice if we had team members with less experience (i.e. every now again there's some advanced fire extuingishing going on).
Anyway, our audience is a low-traffic tech niche and our app is a SPA that's mostly read-only, so that's a very small target that gives us a lot of room for taking chances and picking tech.