How come "which Star Trek were you most into growing up" doesn't make the list?
That's another good option. Plenty of good options out there, especially when you have to rule out certain lists because someone hasn't been involved with that (such as Bond). Could also include first Stephen King movie, first Disney cartoon, and first time being excited about the Super Bowl.
Though now looking at the answers, I feel kind of old because my list is more like:
Star Wars: A New Hope
Batman: Adam West
Bond: Roger Moore
Doctor: Matt Smith
Curry: Annie, technically, though I didn't know him until Rocky Horror
Star Trek: Kirk
Stephen King: The Shining
Disney cartoon: Harder than I thought; probably Sleeping Beauty