Ellis' Midnighter was a little bit too much like Batman, except, of course, he killed people.
Millar's Midnighter is a character who tortures people with industrial equipment and cattle prods, and uses ninja weapons in battle (scoring the odd shuriken shot at the groin of opponents just for the hell of it).
Rather than maintain his cool in an alien attack (the God thing in the last arc of Ellis' run), Midnighter in the fight with the Iron Man surrogate totally psyches him out.
Millar's version is another few steps away from the ever-altruistic Batman.
