Ok...I'll add on to my previous post. First, I would like to preface by stating that the Cena v. Danielson match from Velocity can be thrown out the window- that was not a fair display or either man at his best. Comparing the two, Cena is the stronger of the two. He is a power wrestler; a brawler if you will. Danielson's strength is mat wrestling using submission and wear-down holds. Cena would spend a large majority on the mat being twisted like a pretzel, therefore, severely limiting his power game. It's difficult to throw punches and kicks when your arms and legs are tied in a knot.
Danielson is a thinking man's wrestler while Cena tends to feed more off of adrenaline. Dragon is smarter and quicker, which also gives him a leg up on opponent. Not to mention that, even as a face, Dragon isn't afraid to break the rules and test the limits to gain an advantage, while that's just not Cena's style. He's the role model that 99% of the time, plays by the rules.
RVDgurl's take: If Danielson can keep Cena grounded, he has the advantage. Dragon is not going to win if he trade blows with Cena or plays the power game. I think Dragon keeps Cena off balance and wins a close one by submission.