I'd get familiar with all three. I'd start with PHP. It's ease of deployment will delay the sysadmin stuff that you'll end up learning anyway. Then I'd go to Ruby. Trying PHP first will make you appreciate Ruby and Python more.
When I'm interviewing people, experience in a number of languages is something I look for. A good programmer is a good programmer. Seeing and understanding the ways that different languages have implemented similar concepts makes you form an opinion and see that there are better ways to skin that cat.
I'd get familiar with all three. I'd start with PHP. It's ease of deployment will delay the sysadmin stuff that you'll end up learning anyway. Then I'd go to Ruby. Trying PHP first will make you appreciate Ruby and Python more.
When I'm interviewing people, experience in a number of languages is something I look for. A good programmer is a good programmer. Seeing and understanding the ways that different languages have implemented similar concepts makes you form an opinion and see that there are better ways to skin that cat.