If you go by the scorecard, we have a tie -- Windows 7 and Snow Leopard each win five categories. Of course, going by a scorecard is too simplistic, because not all of the categories carry equal weight.
So which operating system is better? The near-simultaneous release of Snow Leopard and Windows 7 doesn't change the dynamic that has been in place for many years in the operating system competition between Apple and Microsoft.
Snow Leopard is more beautiful and elegant as well as simpler to use -- although with Windows 7, Microsoft has closed the gap between the operating systems, particularly when it comes to taskbar improvements.
Windows 7, on the other hand, remains the corporate standard, and nothing in Snow Leopard is likely to change that. And it's still a more tweakable operating system (although its critics may say that tweaking is mandatory in order to get it running right).
As for me, I'll continue to use both Windows 7 and Snow Leopard. I can't remember another time in which Apple and Microsoft simultaneously released major upgrades to their operating systems. Both releases are big improvements. It's a golden time for operating system aficionados -- my recommendation is to use both and enjoy them if you can.
You can find the complete analysis here.