Just making it known here, but when looking at new phones, the first and most important thing to worry about is hardware. Companies like Samsung and Apple like to show off their software and make that a big selling point, but for the most part if your phone has similar hardware then chances are the software isn't even an issue.
Case and point, I saw that S4 commercial and thought the "Wave to Answer" feature was cool. I went to the Android market, and they've had an app that does that same thing up for nearly a year. It was actually developed on the S3. The point is, most of the fancy software options will either be figured out and copied for all phones eventually or already exist anyway. I think the one exception is multi-window. They have things analogous to that on the market but nothing quite as good.
