I've always made it a point that 32GB is a minimum for me. I prefer too much and not needing it, than having to limit what's on it for the sake of my limited storage. If I'm going to spend over a year with a device, I want to use it MY way, no limits. Feel the same about battery life, data, etc.
For this reason, I'm getting the 32GB version of the MotoX. I hope that AT&T doesn't actually have the exclusivity on it, and if they do, that it's a short lived one. I find that AC has been the only one to say it does. I kinda hope they're wrong on this one. This has a been a surprisingly ambiguous point.