[Samsung Galaxy Nexus] Clyzm:
Keep in mind that not everyone here is buying it outright for $600+, and keep in mind that a lot of people here wouldn't even consider an iPhone instead of Android in general. This post sounds a bit like flame bait, but I'll give you the benefit of the doubt.

My personal reasons are as follows:

Screen: Not just quality (AMOLED), but size. Ever since I had my Samsung Captivate, holding an iPhone has just felt wrong. Everything feels tiny on the iPhone, watching movies is a significantly worse experience etc.

OS: In a nutshell, I prefer Android to iOS. The notification system is better, the multitasking is better (especially in ICS), the OS gives me more options and doesn't hold my hand telling me I'll break my phone if I'm given any more freedoms.

Widgets: Falls in line with OS, but deserves its own category. Why the hell does iOS not have widgets yet? Why don't I have glanceable data on my homescreens such as weather, calendar, and RSS feeds? This is the killer app for me as far as Android is concerned. iOS simply does not compare.

iTunes: I hate it. Especially on PC. I don't like Apple's music format, I don't like being forced to sync content as opposed to drag and drop, and I don't like how iTunes on PC is so badly coded that it completely freezes up and becomes unresponsive while syncing. Something like iTunes should be optional at best.

TV out: the iPhone simply doesn't have it. Connecting my phone to my TV to output youtube videos, emulated SNES, PS1 etc. games, and pictures is a huge boon for the GN. Yes there are alternatives, no they are not as simple as "connect a cable and the picture literally pops up the next second".

General freedom: No emulators or inappropriate content on the iOS market. Yeah, I don't put porn on my phone, but the next guy may want to and he should be able to do so freely without a company scrutinizing his morals. The Android market allows virtually anything as long as it's legal.

Programming freedom: In the same vein as the above, iOS is extremely locked down. There are no custom ROMs, there's no system level tweaking.

As far as drawbacks go:

Camera: Let's face it. The iPhone 4S' camera is best in class. Yes the GN's is faster, but for sheer quality iPhone simply wins hands down.

Touch response: This one may be a bit subjective, but every time I pick up an iPhone I marvel a bit at how smooth it is. Yes ICS is smooth, but I don't feel that it's quite at the same level.

Applications: For sheer quantity, Android is getting there. Quality however, is just now starting to pick up. More triple A developers are starting to realize that Android is a force to be reckoned with, so this is one that will fix itself in time. For the time being however iOS' app selection is simply better.

GPS: Every iPhone I've tried locks instantaneously indoors to a 10-15 meter radius. Every Android phone takes 5 seconds to forever to do the same. It's a minor gripe at best since the GN's GPS is pretty good but it's still technically worse.

That's about all I've got. Also OP, you'll be pleased to know that Android also has a variation of "Find my iPhone". "Where's my Droid" does basically the same thing.