Lot of my favorites are origin stories. I’m a sucker for them and I really think Superman’s got one of the best. But they are by nature hard to argue as essential since there are so many of them. Plus I don’t want my list to be half full of origins so I’ll leave them out.
-Superman TAS
-Superman II since I’m leaving our origins
-Death/Funeral/Reign saga
-For the man who has everything by Alan Moore
-Red Son
-All Star Superman
-Luthor: Man of Steel