Short answer: uname -a
The best Apple OS is definitely Darwin - no matter what name or future name rides on it (ie. Mac OS X). Every bit of stability, pre-emptive scheduling, advanced memory management and even the responsiveness of the Graphical User Interface should be attributed to the Darwin kernel.
Why the Darwin kernel and not talk about the applications, graphics or features? Well that's because anyone's opinion on such "subjective" material could all be true. People can argue about features, applications and graphics till apples turn into oranges; and it's only a matter of time when Linux and Windows catches up with the "nice interface" and "catchy features."
As far as graphics and user friendliness is concerned, I feel that Apple was the best since day one - doesn't matter whether it was an Apple II or Mac OS 9 or Mac OS X. Everyone else just copied.
Yes, sad but true - everyone else just copied.
So how do I judge the best OS then?
- Count the number of times Darwin OS crashes/panics vs. Windows and Linux Measure the system uptime.
- Measure responsiveness of "cool" graphics when heavy background processes are running
- Measure security of the OS.
- Look at code portability (for developers out there - POSIX compliancy)
I'd go on but it's 2:49 AM.
So what's my point? That when the kernel or OS is as rock solid as Darwin, people will love to develop applications on it. Apple's graphics engine will run on it smoother and remains sleek. And well, the end user, remains satisfied always.
Like I said: uname -a
The Great Tiger Giveaway