Apple iPhone 4S (32GB - black, AT&T)

Pros: 8MP Camera shoots the best quality non-point-and-shoot pictures of any device
1080p Video Capture/image stab.
Retina Display
Sleek design (still)
Smoothest OS of any mobile device
Best ecosystem out there: App Store, ease of use, integration, etc.

Cons: Battery life does suffer a little bit. Mine usually gets about 5-7 hours use on top of 16-20 hours standby a day with little battery life to spare.

iMessage seems to not send way more often than normal texts used to pre-iOS 5.

Minor bugs in iOS 5.

Summary: My only issue with this phone is the battery is only about 75% as resilient, at best, as my iPhone 4 running iOS 4 was just months ago. I don't mind that this phone isn't 4G capable because 4G is only about 5-10% as capable as it should/will be in terms of coverage and actual 4G speeds by definition. Another gripe most people have with iPhones that I don't share is the screen size. To me, 3.5" is just fine as I value design more than I do a phone with a 4"+ screen made of some junky plastic (Samsung) or a bunch of different colored metals arranged in an awkward way in attempt to be edgy or something (HTC), and while these claims may make most people write me off as a fanboy as they so often do, I stick to them as my opinion is mine alone.

Bottom line:
If 'lack' of 4G, screen size, and a mediocre battery aren't too big a sacrifice, this is the best smartphone on the market (unless you have a bias against Apple).