Who IS Steve Rogers?

I've been thinking quite a bit about this lately. Because Steve Rogers has been portrayed differently in the MCU, in AVAC, in EMH, in AA, in the comics (all through the years) and even fanfic and fanart, etc - but what makes Steve Rogers - well, Steve Rogers. And why does that make him the best Captain America?

Give me some examples!

Share your favorite episode of EMH or AA or issue of comics, or moment in MCU or even fanfic or fanart (post a link). It would be great to get the board popping again!