RoR is clearly a better language than php from a prgramming standpoint. BUT PHP is perhaps the best supported language on the web. By support I mean platform choices, documentation, discussion, number of programmers, libraries and plugins and stability.

Even though it's the ugly child, you won't go wrong with PHP. It scales, look at facebook. It's where the jobs are.

I hope one day ruby overtakes it, but until then I would vote for PHP.