Well I would say there is no "best choice". ROR got a lot of popularity and yeah you can make solid applications with ROR.
But so you can with other frameworks and languages. Shopware is build on top of symphony ( php) and in the enterprise segement you still find a lot of java applications.
In the end it depends on the application itself and what the requirements are and on your dev team. If you have very experienced ROR developers, you should stay with rails.
Regarding JS technologies, well node, ember, backbone are around for a while now and also proved, that you can make solid apps with js.
However it feels like JS frontend frameworks getting right now more and more popularity, not backend frameworks.