Super Tecmo Bowl was a close 2nd and NBA JAM "He's Heating Up" is third...but my favorite game ever was. SNK Baseball Stars on the Original Nintendo.
(NON SPORTS was Genghis Kahn it was an awesome sim game way before its time!)
It was the first sports game ever to allow you to build a team from scratch and trade players and build up your players just the way you wanted to. I spent months beating up the Lucky Ladies just so I could get my team ready to play the American Dreams with the Babe Lou Mickey Willie Cy and Sandy! The first time I climbed the wall and robbed a homer I almost lost my mind!
I have an original working copy of the game shrink wrapped in plastic in my safe deposit box in my safe today!