C# is the standard language of the Microsoft stack --- in fact, the bulk of MS-stack training is in C#, with only a smattering in VB.NET.
Java is the COBOL of the early 21st Century. It isn't sexy anymore but it will always be around.
PHP is used in a lot of web applications. I wish it weren't. In fact, I'd really rather see Ruby on Rails take over this space.
If you're going to program native code, you could learn Swift, sure. You could also learn Rust (Mozilla's systems-level language with significant buy-in from Samsung) for device programming. If your goal is to write native apps, your best bet for Android is actually Java. By the way, one can also design native apps in Java (the code is Swing-like) and compile them to native apps for iOS or Android using Codename One, and I imagine a few shops will pick up that practice.
I like Erlang as an honorable mention. I'd also add two others: Python (especially for data analysis) and PowerShell (which will set the grown-up Microsoft sysadmins from the point-and-click kids).