RTF is openable in any word processor (pretty much), not just MS Word - hence my preference for TextEdit. It might look slightly different in one or the other, but not in any significant way. As chevy says, it's the content that matters - as long as the layout is clear and easy to read, it's done its job.
You can search and copy text from PDFs just as easily as WP docs. Personally, I'd rather not receive word files from unknown people - too much possibility of virus propagation.
One place I applied at specified that the resume must be bzip2 compressed ascii text. It was a job developing under Linux; I guess they wanted to eliminate the people who couldn't even figure out how to bzip a text file, without even having to read the resumes.
I got an interview, so I guess my resume was good enough (the format was right) but not the job. No surprise, I was so nervous I couldn't begin to sell myself as a good candidate...