gdgt

First pick your carrier. (Wild concept, I know, but you can do that with Android!) If you like AT&T, then Captivate is pretty much it for the time being. Exit flowchart. 8^)

Second, keyboard or no keyboard? If yes, this narrows your choices quite a bit.
T-Mobile: Wait for the G2 in September.
Sprint: Epic.
Verizon: Droid 2.

No keyboard? Lots of choices:
T-Mobile: Vibrant. (Or a Nexus One off of Ebay.)
AT&T: The aforementioned Captivate. (Or a Nexus One off of Ebay.)
Sprint: EVO.
Verizon: What size do you want?
Big: Droid-X.
Average: Incredible (if you can find one).

Or you could downgrade that iPhone back to 3.1.3 and wait a couple months for a bunch of new Dell and HTC phones coming out.

I currently have an EVO 4G and I love it. There is nothing on the market I would currently trade it for. I have never owned an iPhone, but I have played with a lot of my friends iPhones. I would say I definitely like the Android operating system better. The reason for this being the fact that it is so customizable. The one thing I cannot stand about the Apple is the fact that is seems they are running a dictatorship with only allowing you to have what they want you to have. Having widgets on my phone is awesome and I love it. Being able to customize each screen with a lot more then just app icons and folders is also awesome. Plus if you are a Gmail user, then you will find that Android is the phone for you. Gmail, Google Nav (this is worth the switch by itself), Google Places, Google Talk, Google Voice, Google Listen, Google Goggles, Google Translate... all work amazing with Android and it is only going to get better. Also as more and more phones jump to the Android operating system and as they continue to outsell the iOS operating system, the more you will see app developers jump on board and make amazing apps. The only area I would say iPhone is beating Android is in the game app department. But I also see Android catching up sooner than later.

As far as carriers and phones available go I will list my suggestions below. Also when buying an android phone consider the skin on the phone as well as the phone. From everything I read the only company that has a good android skin compared to the stock android skin is HTC with their Sense skin. My phone is an HTC and I think their skin is amazing. I have heard a lot of bad about Motorola and Samsung skins. The build of the HTC phones are also amazing in my opinion.

Verizon- Droid Incredible (HTC Phone) (This phone seems to be the perfect size)

AT&T- Aria (HTC Phone) (My fiance has this phone and she loves it. Only downside is that it is small, 3" screen, and it has no flash or HD video. But the fact that the phone is small is also one of the nicest things about it.)

Sprint- EVO 4G (HTC Phone) (I personally have this phone and it is a powerhouse. It has all the great hardware and software specs. The only downside is that it is a very big phone and if you don't like a big phone then this may not be the one for you. But I love that the screen is so big, great for videos and pictures and web browsing.)

T-Mobile- Best bet would be a Nexus One (Google Phone)

You can't go wrong with any of those phones. Biggest choice for you to make is going to be if you want a small phone and give up some of the power, or have a big phone fully loaded. I personally think the Incredible is great all around. Also check into which provider is the best in your area.

iOS 4.1 comes out next week and is supposed to fix performance issues on the 3G. Time will tell if it actually does.