I'd say both would be a bad choice. But choosing one I'd choose Double Dragon.

Both the NES and arcade versions of Double Dragon are two of the best beat em ups of all time. It'd suck for the games to be remade and then ruined.

Metal Saga would be a decent game if not made by Irem. I've always disliked Irems action or shmup titles because they are always more about memorization on what's going to happen next and less about skill. Makes their games more frusturating than fun.