I guess I'm a pretentious Unix jerk, I've been using it for 20+ years. For me, OSX represents that Unix desktop that should have been. A kick ass desktop environment, that still lets me drop down to a Unix shell.
I never used Macs prior to OSX, but I don't use PCs except for gaming since OSX. OSX is simply my ideal dev/daily environment for anything but gaming.
Oh, and my Mac Pro has a far superior industrial design than virtually any PC I can buy, including high end case mod jobs, wanna-be Antec cases, etc. If I dropped my Mac Pro on top of the majority of PC owner's desktops, it would probably crush it.
My only beef with Apple is not keeping up with top-end GPU releases, and tying expansion devices to whole-machine upgrades (e.g. You can't buy a G8x/G9x for non-PCIE 2.0 Mac Pros, instead you have to buy a new Mac Pro)