MS will give activate your device if you do that email thing on the activation web site and ask them for a new activation. Given how often I get new devices (alot), I've had to have them manually activate my device 20 times already over the last few years
But in the end it doesn't matter which reader is better. Not every book is available in every format. You use whatever reader you need to. If I have a choice, I try to use eReader, but often you don't have a choice.