Transformers Volume 5: Chaos Theory

James Roberts + Alex Milne! Outstanding. Cybertron before the war, the Chaos two-parter, is how you get hooked on the IDW Transformers universe.

Even Mike Costa's Rodimus story is quite good. I think it bears pointing out that little to no human involvement forces the story to be about Cybertronians and that's so much better than anything else in his run.