After a lot of testing and investigating, I decided the clear pick was the Republic Wireless Moto X, a steal at $299 for the phone and just $25 monthly for unlimited 3G service. (I can bump up to 4G if I want, but the truth is I rarely need that kind of speed.)
The real challenge lies in switching to Android after nearly five years of using an iPhone. Though fundamentally similar (it's all just apps and icons), the two operating systems vary greatly in many ways. And I found the transition pretty jarring -- until I made a few key changes. Here's how any long-time iOS user can make Android a little more welcoming:
K-9 Mail for Android tweaked to look like Mail for iOS.