WHAT IS THE BEST SMARTPHONE OS?

Face it: the modern world is run by these devices. VIPs tote them around like second children and do everything from watch Youtube in an airport terminal to fixing up that Powerpoint proposal. The question is: which software does it the best?

(More after the jump).

1. Apple iPhone OS - Now, diehards will refute the statement that this is a smartphone OS, but frankly, there's no denying how powerful it can be. Individual applications can do near anything, with OpenGL support, native WebKit integration, and other various...smart things. If only it could run multiple applications at the same time (and there was an omniscient physical keyboard)...
2. Palm WebOS - Palm came to CES last year at its dying breath, and ended up produced one of the greatest keynote presentions in the show's history, and wowed the tech community with the Palm Pre. And even though no one thought that the aesthetics and grace of the iPhone could be challenged, WebOS's true smartphone capabilities and Javascript-based OS have nearly matched the form and function Apple has produced. The question is whether this OS will sustain itself among the Crackberries of the world.
3. Symbian S60 - Always the dark horse of the OS world, people forget how relatively useful Symbian is until they actually use it. It's functional, it doesn't look half bad, and it still runs solid after all these years. Too bad only Nokia seems to like it...
4. Android - Google has managed to bridge the gap between the iPhone OS and a bit of Windows Mobile--allowing for cute and fun apps as well as solid email (sans Exchange), word processing, and other businessman-like software alike. If anything, it's showing its ability to be the most versatile smartphone OS at the moment.
5. Windows Mobile - I used to be a hater (e.g. my Samsung Propel Pro review), but after seeing a running build of 6.5 running on a Touch Pro...I was slightly convinced of its value in society. It actually appears to operate as a portable version of Windows like they say it should, rather than the turdbasket of an OS that graced the first 6.1 versions of the software. Here's hoping that with 6.5 and 7 they take back dominance in the smartphone industry.
6. Blackberry OS - Blackberry has been using the same kernel (with minor occasional alterations) for years on their entire range of smartphones, and frankly, this is the one that businesses rely on the most. They have consistently allowed for businessmen of all types to remain connected and capable of communication at all times, and nowadays their hope is to retain that audience while branching out and ripping those tweens away from their RAZRs. To top that of, RIM is one of the most successful companies anywhere in any industry, so that says something about their products.

So what do you think, readership? Which is the best?