That's a tough one there, as they are both some of my favorite characters. Though I think them not being alive leaves a better impact, as they both died for good causes. Them being alive would make it less memorable so I'd say neither.
6/6 have voted Itachi. Hah! I love Minato, but i feel the story and Sasuke would benefit more from Itachi returning than the story and Naruto would from Minato. Besides, Itachi is one of my favourites.