Template engines allow for easy and flexible UI building.
The MIT License is a very permissive license which allows all uses, including business use, without warranty.
Built-in utilities to help validate client input before it gets processed or sent to a server. While this does not replace server-side validation, it can vastly improve the user experience.
Legacy browser support can be important for corporate projects and projects with a large user base consisting of Internet Explorer users.
The major version number is above 0. This means there will be no compatibility breaking API changes introduced by the development team.
Other frameworks might be locked with a template engine you don’t like and there is nothing you can do about it.
Includes utilities to keep models in sync with their server-side representation without the need of writing jQuery boilerplate ajax calls.
Bower is an easy-to-use, npm-like package manager for frontend applications.
The node package manager can also be used for managing front end scripts.
Asynchronous Module Definition libraries allow for easy modular, clean programming. If a framework does not work well with such libraries, it might have some other means to modularize its components and resolve dependencies, like Dependency Injection.
Views can be bound to update automatically when an observable object changes.
Models are observed for changes. This is a well known pattern. Can be more performant than dirty-checking in some cases.
Smaller file size means faster load times.
Routing allows interaction with the browser url. This is very important for a good user experience if you are building one-page apps.
Supports a template engine that can be pre-rendered on the server. This possibly improves page speed, especially on devices with low computing power.
Less dependencies means less extra scripts to include, usually resulting in less development overhead and faster load times.