We've been using an html5 game engine called Phaser for over a year. It's open source and was created by a photon storm.
Our experiences with Phaser have been fantastic. We've tried several frameworks but found Phaser the best game engine to develop our games from the usability and performance points of view.
Now Richard Davey, the man behind Phaser, has started a campaign to collect money to be able to dedicate more time enhancing his incredible framework.
Please check this out:
>> Phaser on Patreon