Battery Percentage!
One of the things I missed about iOS/iPhone 4S is the ability to see how much battery life you have left, in numbers.
Android phones don't have the option to do this. I guess they don't need to since many phones have terrible battery life.
I have the battery percentage enabled. I'm a bit OCD with my battery since I use my phone a lot at work. I guess that's why I have a USB cable to charge my phone at work and a car charger as well.