What is the best way to develop mobile 2d games?

Question

Mobile development

Choosing a technology for developing mobile 2d games - casual games.
Basic criteria:
- performance
- development speed
- cross-platform
Flash (air starling) - performance sags a lot if you want beauty (complex animations, effects) - not suitable
We investigated the unit: normal 2d by the engine itself more or less appeared only from version 5. NGui has performance issues, 2dtoolkit is not very friendly with particles, etc.
It is interesting to collect statistics - who develops casual games on what (candycrush, twodots, pheoms without 3d, etc.), what is good, what is bad?
Native development is also of interest, large players often choose it.
UPD:We consider both paid and free engines, the only thing is that the "% of income" model does not fit

Answer 1

Unity you somehow described too harshly, more than suitable for your purposes. LibGDX - plus.
If you need a social network (web), you can watch html5 + cocoon.