Droid- I've never had an iPhone, but kids had Ipod touch 4G... and that was enough.

no replaceable battery? WTF?
Interface just feels... insulting... been that way every since Mac came out, so it's probably a prejudice on my part
does the iPhone allow memory upgrades (micro SD or the like), or is that just the iPod that doesn't do that?
and Flash (probably the single biggest mistake)
iTunes and the app store just piss me off

I just got a Droid this weekend, already like it way better than the iStuff (Yes, I work for a phone Co. but their service doesn't work at my house)