Cyclops as dark from the end of AvX, versus dark pheonix jean from the dark pheonix saga or wherever she is most powerful.
For me, the whole idea of the P5 was pretty cool, and I will take any of them (specially Scott and Emma) instead of Jean anytime. BUT, still she is pretty much THE Phoenix, and the one with the best feats. Phoenix/Dark Phoenix Scott is cooler, but still Dark Jean is stronger. He wasn't given the time or the opportunity to prove it otherwise.