I don't think it's the right answer to approach this looking just at their abilities. Gladiator will function off of a mix of DMG, Blocking, Emnity generating abilities, and some healing from the Paladin job, Marauder looks to function off of High AoE DMG, Parry, Few Emnity generating abilities, and some more DMG for kicks. I noticed you failed to mention PUG tanking at all, I wonder if it's an oversight on your party or you just think SE is joking by giving them native tanking abilities still.