In my opinion, right now, it's the Samsung Galaxy S. It's currently the fastest Android hardware, has a GPU *way* faster than any other Android phone. Currently the Nexus One with Android 2.2. can run faster in certain situations, but the SGS is due for Android 2.2. before the end of the year. The SGS has the best screen by far of any phone on the planet, in every category that I can think of. Oh, and it eats iPhone 4s for breakfast.