The thing is it was only a year ago when the iPhone was without a doubt the best smartphone to get on the market. But in that past year, Android has finally caught up with the Nexus and Galaxy S III and such. The iPhone and the top of the line Android phones are all pretty equal right now. There really is no "best phone" anymore, it all comes down to personal preference.
Personally, I'll be upgrading to the 5 from my 4. Android phones haven't shown me a reason to switch over from iOS, although if you're an Android user, there isn't much incentive to switch over to iOS either. However, when my next upgrade rolls around, and if Android shows they offer better products than the iPhone, I wouldn't mind switching over.
It's because some people have to justify their purchases, no matter how stupid they sound.
I agree with everything except about the 4S. Personally I thought it was a step backwards from the 4. The truth is that as you said there is
not much of a difference between Android and Apple phones anymore. When the 4 came out it was lightyears ahead of Android phones. It was the first phone I had that was incredibly quick, beautiful, had all day battery (whereas even the 4S battery sucks in comparison), and basically everything just worked.
Since ICS and beyond Android phones are at that point, with maybe the exception of all day battery (and let's be honest, some of their phones have at least 4S of better battery).
I am going with the 5 because I hate my 4S and also because I hope to get better battery life, but after playing around with the last Nexus I don't think it would be hard for most people to switch back and forth. Unless you need to host torrents on your phone or alternatively unless you need iOS only apps, there are a lot of phones that will meet your need.
The truth is that Apple has not blown us away since the 4, but neither have Google or MS. Right now things seem to be pretty static and it is anyone's guess as to who will make the next big thing. And if MS can get more support people will have 3 good options.