Certainly not Android.
With Froyo, the user experience was good on the EVO. With Gingerbread, the buggy, laggy, life sucking abyss is an unsatisfying user experience that doesn't inspire the desire to go through it again. The only other platform that seems to be concerned with "user experience" at this point is Windows Mobile. Black Berry doesn't cut it (been there and done that) and who knows what will happen with WebOS. So if it wasn't the iPhone and a Windows Mobile device that I like was on Sprint, that would be it.