[Romoku]

Knockout is my go to library when I need data binding. It's lightweight and doesn't interfere with your markup.

[stoodder]

This is my favorite 'feature' of knockout. It's as simple as knowing a single attribute 'data-bind' or comment pattern '<!-- ko ... -->'. The only down side that I've seen is not having an 'else' statement :/. That's just a by-product of how knockout's bindings work though and hasn't stopped me once from keeping it my preferred library.