I'm a developer who develops in both! I maintain a lot of legacy sites built in PHP, also there are apps I commonly use like WordPress that are PHP. It's _very_ accessible for beginners, and the documentation at php.net is fabulous. If you have zero programming background this is a very reasonable choice.
Ruby is a more difficult language to learn if you're starting from zero. And I want to point out there are other ruby frameworks to use besides Rails (minimalist framework Sinatra is really great) But rails is a good choice for beginners because they've made so many decisions for you, based on common best practices. Things that take a long time to build in PHP are done in seconds or minutes in rails, so productivity is high.
Finally it should be noted that there are frameworks for PHP, although they don't seem to be popular, and I can't comment on them because I haven't tried them. CakePHP is the one I usually hear about. Also if you took a Python class in college somewhere, then go for Django, their popular framework.
have fun!