Beast and Storm are two others that I can think of that have to choose sides

In all honesty I will probably break down and buy the event's main series just so I can keep up with what's going on in Marvel. I'm already reading Avengers X-Sanction and Avengers Children's Crusade which I think are both pretty much leading up to AvX. I have room in my budget to add more to my pull list, so I might as well read AvX.