Nexus One: This phone will always allow you to test out the newest updates with the least amount of pain. You'll always have the newest updates soonest. Downsi

Nexus One: This phone will always allow you to test out the newest updates with the least amount of pain. You'll always have the newest updates soonest. Downside, however, is that any particular advantages / disadvantages won't really reflect the broader Android install base, since there are so few Nexus Ones. But there are relatively few serious problems that come with fragmentation when you are considering the 2010 crop of Android phones -- between all the big names, everything should work pretty well. Getting a Droid (the original Motorola one) can give you a taste of what many, many people have and are using, same can be said if you got an Evo, DroidX, etc... And it can be a worthwhile experience to see how performance might differ when burdened by the skins (MotoBlur, Sense) that are on the phones as well.