Since you're already on AT&T and don't mind staying I wonder if you could buy one phone and try it out for a couple weeks and then take it back and try another. That's the only way to really find out about each (Android vs. iOS) since most discussion on the internet about them has reached emacs vs. vi level.
I'm not sure how it would be if I couldn't as every so often i do sync some music or movies. But cloud services are making iTunes and the USB cable more and more irrelevant.
It's a shame Apple is so bad at cloud services itself.
Software upgrades require iTunes, but I guess as long as you have access to an iTunes equipped box sometimes. As you point out, if you're dependant on adding Music and Movies frequently it would become a pain in the ass.
I know you can use Rhythmbox to sync music and videos to the device. Not sure about apps, but you can definitely just download apps on the device itself. Also, I hear iTunes runs fine in Wine, so that's also an option.