Personally, after playing around with all kinds of game engines and frameworks, I always go back to Unity. It has a lot of warts and issues, but for me it's the most productive way to focus on actually creating games.
What I'm interested in mostly is if I at least got a significant performance gain from chosing SpriteKit over Unity.
The same author is working in Cocos2d-x and Cocos2d-iPhone
That was in the past, AFAIK Ricardo works only on Cocos2d-x now. Cocos2d-iPhone is community driven now.