It always makes me chuckle when I see the PHP guys suggesting that theirs is the better platform because its cross platform, cheaper and more wide spread.

The funny thing about this is who would you rather be working for anyway? The company that spends tens of thousands on server and software infrastructure or one that signs up to one of the many, many shared hosting companies run by 2 guys in a basement somewhere. Php hosting company's are everywhere because its cheap for them to set up.

Now, for my suggestion...

Php all the way!!! You'll get paid less, you will *probably* not ever learn as much or be as good a developer as the Java/.NET guys, but you'll likely enjoy your job more. Why? Because you will likely be working in some easy going new media company where everyone goes for drinks on a daily basis and there are even a few hot women scattered around.

If you do choose the .NET route though, learn Java in parallel as there are major similarities. Oh, and avoid the WebForms framework like the plague (look at MonoRail or ASP.NT MVC).