Quite the rebellious thread... I like it!
As an AT&T customer, my first iPhone was the debut model back in 2007, and I've owned every model released since then up to the 4s. I plan on getting the 5 when it comes out this year. I'm pretty much ingrained to he iPhone and I do enjoy it's features.
With that said, my fiancée is with T-mobile (parents' family plan) and she owns the Samsung Galaxy SII. I have to say that it's a pretty impressive phone based on the features listed on this thread. And I believe that Samsung makes quality products. Most of my phones before the iPhone were Samsung and have never given me problems. I don't have much experience with Android devices or their OS but my fiancée definitely prefers it over iOS. She's looking forward to the SIII (and so am I, lol!). I did get a chance to play around with a friend's Galaxy Note. I can see why folks are referring to it as the iPad Nano.
Now IF I were to jump ship, I would go with Siri's recommendation of the "best smart phone ever"

the Nokia Lumia 900. Yes, it's Windows-based, but wow, it's is dang impressive. Even the magazine Mac Life has dubbed it the "iPhone killer"! And that's saying a lot coming from a publication dedicated to all things Apple. They had a full review on it and gave it some impressive accolades, particularly the feature that it can be integrated with iOS devices (like the iPad). They even preferred the display over the 4s. Let's see what the iPhone 5 brings to the table...
All in all, I share the sentiment that we can enjoy multiple platforms. Market competition is good,it keeps product developers on their toes, and we the consumer benefit from these latest tech advancements with every product improvement.