GSAP is an animation platform created at one time for Action Script, now ported to JS.
Able to animate the properties of absolutely any object, convenient to use, light in weight and, most importantly, very nimble.
Speed ​​test.

It should also be noted:
cross-browser compatibility (works in all browsers starting from ie6);
absolute independence from other frameworks;
the ability to organize and manage timeline - layout of animations into a single whole at the discretion of the developer;
low weight (for example, the version of TweenLite.min weighs 21kb today);
convenient and intuitive API, excellent documentation;
plug-ins (Bezier curves, Raphael plugin, cssRules plugin);
... as well as an understandable and accessible tutorial.