I have a simple order of operating system preference –
OS X does what I want. It’s polished, it works and doesn’t get in the way. Linux (with GNOME) is similar, but with less of the software I use. To be honest the lack of Photoshop and spotify are the real killers, and GIMP is no Photoshop. I feel bad about the lack of open source goodness, but not too much. Linux has no compelling application to make me want to use it, yet somehow I keep installing the new version of Ubuntu (then tweaking it to work properly to work with my MacBook, then realising that OSX takes no effort to set up).
Windows I can take or leave, but frankly I’d rather leave it. I have my MacBook setup to dual boot, but haven’t used Windows for more than 30 minutes since I installed it a few months ago.
My point (I may have one) is that linux lacks a killer app. Amarok used to be it, but iTunes is now pretty good I absolutely cannot do without Spotify (running it through WINE feels dirty). Compiz (or whatever it’s now called) is pretty, but exposé is more usable. OpenOffice is equally ‘not quite MS Office’ on all platforms, but there is no replacement for Apple iWork on Linux or Windows.
Even without a killer app, Linux comes a close second to OS X. All it needs is a decent UI and a decent interface for GIMP, a native Spotify and something competitive with iWork. The rest is just polish. The Acer Aspire One running Linux is superbly delicious though. Who do I kill to get one?