AmpersandJS (http://ampersandjs.com http://ampersandjs.com), which is more a set of rules for modular libraries than a framework (but it's still a framework).

AmpersandJS (http://ampersandjs.com http://ampersandjs.com), which is more a set of rules for modular libraries than a framework (but it's still a framework). 1. One or two weeks to learn and let it start sinking in. 2. Speed: probably 3. I can make the code do what it needs to without much effort. 3. Quite maintainable. In fact, I've contributed a few bug fixes and feature improvements to the source repos. In my own code, making changes also happens quickly. 4. I chose it after reading Human Javascript (http://humanjavascript.com http://humanjavascript.com) (which AmpersandJS is based on) and poking around with the boilerplate generator app. It all instantly clicked.