What Language would you learn?

I’ve spent years in the Networking/System Admin world. This year I’m
challenging myself to do something new. This year I want to learn a
programming language. My work is big on .Net but rumored to be
going to Java. I’ve dabbled with PHP. Recently I’ve read that learning
Ruby on Rails is the way to go. I need help!

So if you were me, what language would you learn?