I want an Evo!!!
I can't narrow it down to one feature, rather it is a combination of many that have me considering the switch from Apple and AT&T. This combination of features is the 8mp still camera with the 720p/HDMI-out video capability. That and the ability to swap 32gb storage cards means this is the first phone that really replaces the need to carry a separate camera for 90% of situations. I have had my iPhone 3G for two years and I have loved it through and through, but it is really showing its age in terms of hardware and software. I would like to wait for their announcement on 6/7, but the combination of hardware specs, service pricing and the fact that I live in a well-covered 4G area (Chicago) makes it very difficult. From what I've heard of the new iPhone, it will have to sport some sort of compelling feature for me to consider not switching. In either case, I want an Evo!!!