One can get away with jQuery or plain DOM juggling for the simpler web projects. There's plenty of choice when you're up to a full blown MVC-ish application. But what to use when building complex web sites (as aposed to applications, though not sure about the terminology) that aren't straight single page yet do more than some occasional ajax requests? E.g. something like soundcloud.com.<p>I dealt with Ember and have less experience with other majors - would any of Angular, Backbone, etc be a good fit? Or custom tools is the way to go.