Trending Backend Technology for Web App Development [on hold]

I am looking forward to build an app, it would be both Web and Mobile(iOS/Android) which require some real time feature and it will be handling lots of datas simultaneously and feature to sync user profile across the devices. There are lots of options out there but i am hearing many good things about node.js i have good understanding and experience with PHP and ruby on rails on backend, i have some knowledge on Meteor.js as well which is also a node.js framework but i am not yet ready to implement it in my new app as i see some hurdles in near future. I am planing to consider react.js for the front end, as many suggests it is light weight and better alternative to angular and ember. I was hoping if anyone could give me advice on picking up backend language considering latest scenario and evolving development scene. If it is node.js are there any popular frameworks for node.js for backend only (assuming meteor as full stack). And as i am starting this app from scratch can you also give me some advice on picking databases as well. I have good knowledge on MongoDB and MySQL.