Same here. It will be pretty awesome to see how creative Kindt can get with their powers.
Just go for whichever you want. They're all strong starts but just in case the order in which they were published was X-O, Harbinger, Bloodshot, then A&A. You don't have to worry about the order until you get to volume 3 of Bloodshot and Harbinger since they crossover during Harbinger Wars.