Heavy armor. One lightsaber. Shown to be able to taken massive amounts of punishment. Force Push.
This. Also, in the Return trailer he was almost forced to use two lightsabers, to be on par with his adversary. If he was a marauder he would have kept using two lightsabers.
All of this being said, no character can really be defined by a class (as mentioned above, he uses lightning but neither marauders nor juggernauts can do so). They are a game mechanic detached, at least partially, from canon lore.