I am on Sprint, and recently swapped out the EVO for the iphone 4s. Much happier with the iphone. The 4G on the EVO was nice when I was on the road in a larger city that had good coverage, but that benefit did not out weigh the far superior battery life (like a bagillion times better), better apps (the same apps on iphone are worlds better than android), and just general "usability."
Happy with my decision.