Ask HN: Which language/framework to learn in 2016? Python, Ruby, or JS/Node?

I'm a frontend developer who is looking to get into server side programming. I have some experience with PHP, but am looking to get more serious about learning a language/framework/stack for the backend stuff.

I've done a lot of googling, and am trying to decide what the best language/framework would be for the following criteria: - Potential salary - Job prospects, both now and in the future - Ease of learning/amount of time it would take

So far, the results of my research have been mixed. Node seems like the hot new thing, while Python returns the most search results by far on any job listing site. Forum posts say that Rails seems to be dying off, but I see a lot of job listings for that as well.

I've always wondered, what stacks do the people making crazy salaries out in Silicon Valley use? I'm willing to learn whatever is best for my career.

Any advice would be highly appreciated.