I don't think they are comparable. Master is significantly better at high levels where his damage is competitive or beats Knight, while if you look at the hard numbers early on, Black Belt doesn't do nearly as much damage as Red Mage or Fighter early on and has no heavy armor to compensate for this. My conclusion is that the Blackbelt is weak early on and at the end (Unless you grind forever) but strong in the midgame, Red Mage is solid throughout but weak at the very end, and Thief is terrible until near the end of the game. Thus, Red Mage is the closest Final Fantasy class with a similarity to Marcus.
If you are interested in my reasoning, from examining the difficult portions of the game (Marsh Cave, Earth Cave, Ice Cave, Chaos) it doesn't take much stretching to see who comes out on top at various points.
Black Belt is near useless in the Marsh Cave since his damage is still so low and the Piscodemons have high physical attack power it can't deal with, while Red Mage can tank some shots and use Fire on Creeps. In fact, BB is basically the same as Thief there since neither is accomplishing too much.
In the Earth Cave, the Black Belt starts to catch up some in damage, but Thief now has access to weapons obtained from the Magic Key, making him slightly better; he's a Red Mage with no magic. Red Mage is still above both of them since he has multitarget spells available where you might really need them against Cocatrices and such.
In the Ice Cave, the danger is mostly enemies that can one-shot you or win on first strikes with MT damage, so any team sucks there anyway. Seriously.
Finally, against Chaos the Ninja is probably the best overall since it has Haste and can equip good armor. If you grind out to high levels, Master might beat it, but there's really no need. Red Wizard does fall behind there since he's basically just a Haste caster/weak attacker at that point in the game. (Haste is the only valid way of doing mass damage reliably, so it must be considered the most important strategy at that point since Chaos can recover all of his HP at random)