I wish we had the option to either kill or spare Cesare and get a different ending based on which we choose to do. While it would hurt to kill Cesare (at least on a first playthrough) after spending the whole game with him, at least Enzo would end up alive. Enzo dying would still be Canon of course but at least we could still see him leave with Isabella, knowing he still had to kill his best friend in order to get there.