Who knows? Current Danny is like a different character now, what with the womanizing antics and throwing out DBZ like chi attacks.
If you asked me before the Marvel reboot, I'd have said Rand.. He was learning a lot of tricks from the Book of the Iron Fist, and it was implied he sub consciously was holding back because of what the girl told him. And during that Iron Fist killer story, Fat Cobra does struggle against the killer, and seems to get taken out with several chops to the throat, while Rand was able to eventually beat the killer.
Also, Danny knocked out Cobra when the two met the Son Wukong, the Monkey King. Although Cobra's powers were inhibited, he was still strong enough to send Danny flying with a palm strike to the chest.