Looks like there aren't many Operating System fans around.

Windows 7 is really nice. I've been using the RC for quite a while now and really like what direction Microsoft is taking with it. I've always been a fan of the OS X dock, so I'm pretty happy with the new task bar. If I had the choice I'd use Mac OS X, though. Prettiest OS I ever used. If only Macs weren't so expensive

Has anyone ever checked out BeOS? I used to love it back in 2000 or whenever I tried it. Though the original OS is no more the Haiku project has been making progress and released an Alpha version of a complete rewrite of the OS. Though for now there's not much you can do with it and a lot of drivers are still missing, etc.: Haiku Project | Home of the Haiku Operating System