I will third/fourth/who cares, for Arch. I use it for embedded stuff, and is a great learning process.
For hacking specifically, BackTrack is very widely used, but again AFAIK is also Debian based. I think going with Arch, then installing/compiling the tools you need for hacking such as AirCrackNG or OLMHashCat would be best. BackTrack has loads of tools yes, but you really aren't going to use that many. Going with the Arch manifesto as in install only what you need is my preference.
I personally am using Ubuntu as my OS for my desktop at the moment, and will put Arch on the Desktop/Laptop when I get a new one here soon.