I think Obviel comes out pretty nicely in this particular set of criteria, but of course many other criteria exist.
A declarative approach where the UI is updated when the underlying model changes.
Obviel provides this because views can listen to events on models. When a model is updated, an event can be sent to the model. If a view is currently representing the model in the UI, that view will be notified. A typical response by the view can be to rerender itself, but more detailed updates exist as well.
Then there's Obviel Sync. Obviel Sync is a library that lets you declaratively bind models to some backend, typically a server. Using Obviel Sync you can automate the sending of events to models. Unfortunately Obviel Sync is as yet undocumented (the only part of Obviel not to have docs) and needs a bit more polishing. If you're interested in helping out, let me know!
While there is still a lot of potential in further expanding this approach, I think Obviel already has a pass mark on this feature.
Compose views (preferably at the template layer). This should entail the potential for a rich view component hierarchy.
Obviel is built around the concept of composing views, and the template layer supports this. A central trick in Obviel is that the view to use for a model is determined by looking at that model - if you swap in a different model, a different view will be rendered. The code that renders the view doesn't need to know or care what specific view is used.
This can be driven from the template layer, by using the data-view directive.
You can create rich view components with Obviel; more about this in the next section.
A definite pass for Obviel on this feature.
No native-style widgets, but instead let people use HTML and CSS.
What the right approach here is a debatable topic. Some client-side web frameworks provide a whole widget abstraction and you build the user interfact by composing those widgets together. Others are explicitly centered around HTML and templating. Both approaches have their advantages and disadvantages.
That said, it is possible to create widgets on top of Obviel, using Obviel Views. The Obviel Forms library is an example of such an approach. Another very interesting up and coming library created by Rob Gietema, Obviel Bootstrap, creates a set of Obviel views for Bootstrap UI elements. Note that you don't have to use Obviel Bootstrap to use Bootstrap with Obviel; instead you can directly use the bootstrap css classes in the HTML of the templates.
So, a pass for Obviel; Obviel's designed this way.
jQuery is pretty amazing. I want a framework which recommends using jQuery itself instead of providing its own sub-par jQuery clone.
Obviel is built on jQuery, so that's an easy pass for Obviel. jQuery extends jQuery in a small but powerful way by letting you do $(el).render(obj) to render a view on an element for an object.
Obviel passes on this one by design again.