Dragon is the leader of the Revolutionary Army, and also is a great threat to World Government. He was first introduced at Logue Town. During the time when Blackbeard Pirates attacked Baltigo, it was said in the newspaper that there were no casualties. Dragon might have confronted Blackbeard himself. And in my opinion Kizaru doesn’t stand a chance with Dragon.
Marco was the former first Division Commander, and captain of the Whitebeard Pirates, after Whitebeard’s death. During the battle of Marineford, Marco was one of two people who fought toe to toe against Kizaru. Marco can also use Armament, and Observation Haki. He also possesses a Mythical Zoan type of Devil Fruit which allows him to turn into a Phoenix and with which he is able to heal from any damage. If Marco and Admiral Kizaru fought again, Marco might be able to defeat him and also it would be a fight to remember.