YUI3 is more of a framework than a complete solution, but personally I prefer it that way. It offers more flexibility.
Here's a post on defining your template within the html itself using yui3. http://lostsyntax.net/posts/5
I will admit I had a little trouble with that approach, and ended up defining my "templates" as strings within the javascript itself for unscatter.com. That's how the paging works for javascript enabled clients.
If you are really after MVC, from what I've read of them I think SproutCore probably comes the closest.
I think though, you need to consider the environment you're working in. Programming a system that will run on a server is much different that programming an application that will run on a personal computer, laptop or even mobile device. You're generally bound to a single core with limited memory availability. Syntactic sugar leading to faster development time is generally a good compromise on the server side, but on the front end you have to be careful. This warning isn't an attempt to disuade you from the existing frameworks listed, or even to keep you from writing your own. It's just meant to advise you of something to keep in mind while you do your application development. Know your box, and excel inside it.