On my current project, I would really like to move away from YUI and towards Backbone.js. I am a believer in using a hybrid approach of the best components instead of using a single monolithic library.

YUI is a large, heavy framework that enforces their way of development. While their way isn't wrong, it does makes us beholden to Yahoo and their choices. YUI has incorporated much of Backbone.js into their later releases but it is significantly behind where Backbone.js is. It is also forced into the existing YUI structure and conflicts with other YUI components. While it does have good community support, it doesn't compare to the more mainstream libraries in the JavaScript community.

I want to move forward using a hybrid model. We would choose the best components and keep our options open to better items as they develop. I want to use Backbone.js for the app structure (models, views, router). This lets us use jQuery for DOM manipulation and progressive enhancements (not app structure). Our CSS will continue using Bootstrap components.

This is a lighter-weight approach, both in terms of library size and future development.