Debian, RedHat, and Suse. I also run Windows. But I don't use them much any more. I have moved on to Mac OS X as my main system.
Ten years ago a Linux geek that I knew told me that in the future I would be using Mac OS X as my main system. It only took my ten years to realize that he was correct.
For the skeptical such as myself, I think that running a bunch of Linux distros is the best route to the Mac.
I’ve tried Fedora, Ubuntu, and Linux Mint. Of those, I really liked Mint best, but it wouldn’t recognize the wireless card on my laptop. Then I found PCLinuxOS and love it. Not being a geek, and hearing the horror stories, I thought the transition would be much more difficult than it was.
Another benefit, this whole experience (and I did do this initially solely as a learning exercise) has me *wanting* to learn more about computers. So I got hold of a really good (and free) booklet on using the terminal (http://people.wallawalla.edu/~larry.aamodt/engr122/TLCL-09.12.pdf). Maybe I’ll eventually turn into a geek after all....
I’ve used Linux for years, but recently got a MacBook Air so I have something small, light and reliable for use out in the field.
I can’t wait to get my new desktop machine so I can get back to Linux.
Mac OS X is not horrible, but it’s not the pinnacle of perfection that it’s claimed to be. And it’s not very configurable.