I would say get the gripz over the other 2. The last thing you want is to be setting up those goofy rings and have someone confuse you for being a retarded orangutang, err uh I mean crossfitter.
This thread shoulda been more like:
Fat Gripz, Rings, and TRX
You gotta fuck one, marry one, and kill one.... k go!
I love fat gripz. They are insane for Kroc rows.
I also use them for weighted chin ups for a few weeks. When you go back to ordinary chin ups after 3-6 weeks of fat gripz you're sure to break a PR.
Without Fat Gripz I would not be able to press pain free. So Fat Gripz.