Some great answers here!
A long list for me, in semi-chronological order:
01 Just about any Superman comic, but especially the Golden Age for the simplicity being so dynamic
02 The Adventures of Superman (because I grew up watching reruns of George Reeves)
03 Superman: The Movie
04 The John Williams Score (mentioned separately because it's that damn good)
05 Super Powers Superman (and related) action figures: that was my first Superman figure, and I think I had about 8 of them and one Clark Kent, lol
06 The Ruby-Spears Superman cartoon
07 The Triangle Era of Comics
08 The fun of "Reign of the Supermen" (that totally duped me into thinking Cyborg was going to end up being Superman, LOL, also see #7)
09 Dan Jurgens/Brett Breeding art (writing, too, for Dan)
10 All-Star Superman
11 Superman: The Wedding Album
12 Infinite Crisis: didn't like Pre-Flashpoint much, but Infinite Crisis was a fun ride!
13 Parts of Final Crisis: Legion of Three Worlds and small moments in Grounded (which reminded me my favorite Metropolis moments in Byrne's "Man of Steel")
14 DC Universe Online (because I can fly around Metropolis and "see" all the landmarks from the comics, but the game's just a lot of fun in general -
just redecorated my "Fortress of Solitude" base)
15 Convergence (see #7)
16 Superman: Lois and Clark because "my" Superman had a place again (see #7)
17 Superman: Rebirth (because it took exactly that to get me fully back into the books again, also see #7 lol)
18 Superman: Reborn (hopefully the start of a perma-merged Superman that will eventually be something of a unifier)
19 Superman's "voice" by Bendis (probably the closest to what I see Superman's voice being that I've ever seen, and that's saying something!)
20 Metropolis, IL Superman Celebration (yearly): So much fun talking geekery all weekend (comics/media discussions usually from 10pm to 7am in the hotel lobby, lol) and just generally having Super fun. Always a good time.
21 Super-suit & Super-Reactions: I love the Superman suit my mother and grandmother made for me (see my avatar pic) back in '95 (especially seeing how my grandmother passed away 6 years ago).. it's both classic and just amazingly regal without looking "stuffy". It's 24 years old this year, but it's still majestic. And there's just something about being in that costume and seeing kids (and even grown-ups) get wrapped up "in the moment" and their eyes are full of joy, hope, wonder, and positivity. The feeling that gives off to see people like that is just so powerful and beautiful, and to have played some small part in that, even moreso. And playing the John Williams theme from my cell phone moto mod speaker tucked into my costume belt is fun, watching people wonder where it's coming from, lol!
I'm sure there are so many that I'm forgetting... but those are all big ones.