I voted Mac. Karthadast is, imho, too much like the romans. If you play as Mac you will have makedonian-style phalaxes, very good cav, as well some of the best/coolest elite units in the game!

Karth also have a great setup, and is really fun to play. But as I said, you will pretty much fight over the same land, with pretty much the same kind of units as the romans.