Sad though it is, the best looking one (in my opinion) is still the Windows 1.0 logo.
Also, I agree with MG, why don’t they just jump off the fucking boat and ditch the Windows name? Seriously. With all the baggage that brand brings with it, are they really money ahead by sticking with it? Microsoft is the brand they should be worried about, Windows is merely a product, and one that people don’t generally hold in close regard anyway.
This isn’t a new idea. The time to rebrand and reinvent is now; Metro is trendy enough for them to badge their new UI with it, think of what it could have done for perceptions of the OS.
What’s next? Windows 9? Great, then what? Windows X? Yeah, that might be a bit of a stretch…