I was ExtJS developers for about 4 years, and for me it was shock when I realized that ExtJS is dying, but it still alive just less used. I think all is going like - framework A is no anymore number one, framework B is next. And this lifecircle is about 3 years, but it is just trend. It does not mean that framework A can not do the same that B does.

I like ZingChart more than HighCharts, because In ZingChart there is very advanced self theme doing. It supports very big data even on 1 000 000. It has many types of charts and many samples .