That's a big milestone point for the character. And it made me realize that barring something unexpected, I will be alive to see the 100th anniversary.
But enough of my analyses of time being a thing that exists. In the spirit of this milestone, I would like to propose some questions for the replies, with my own answers as an example.
Favorite in-continuity Superman story: Either Up in the Sky, For the Man Who Has Everything, or What's So Funny About Truth, Justice, and the American Way? They all represent aspects of the character that I consider to be very important.
Favorite out-of-continuity Superman story: All-Star Superman. Both for the reason given above, and because I like the way that it treats him almost like a mythic hero, tying into an idea that ran throughout other comics of the time if superheroes being a modern mythology.
Favorite Superman writer: Either Grant Morrison, Tom King, or maybe Dan Jurgens, but I've been meaning to re-read his time on Superman, as its been a while.
Favorite Superman comic era: Probably the early "Triangle Era" from the early 90s. Up in the Sky might have been the story that made me like Superman as a character, but the Triangle Era was what got me into the character's wider mythos.
Favorite live action Superman adaptation: Either Superman: The Movie (1978) or Superman & Lois. Both of them represent aspects of the character that I consider to be the most important incredibly well.
Favorite animated Superman adaptation: Superman: The Animated Series. This series just works. I would even go as ar as to say this is one of the definitive takes on the character up there with All-Star, FTMWHE, and the first Richard Donner movie.