Someone hit me with this question the other day.
NES - Tecmo Super Bowl (thousands and thousands of hours spent, literally. Still have the same cartridge and played it last week)
SNES (didn't have one growing up) Mario World/U.N. Squadron tie
Sega Genesis - Joe Montana Footbal '94
PS1 - Tony Hawk Pro Skater 1
Xbox - MLB 2k5
PS2 - NCAA 2005
360 - Fight Night Round 4
NES - Tecmo Super Bowl (thousands and thousands of hours spent, literally. Still have the same cartridge and played it last week)
SNES (didn't have one growing up) Mario World/U.N. Squadron tie
Sega Genesis - Joe Montana Footbal '94
PS1 - Tony Hawk Pro Skater 1
Xbox - MLB 2k5
PS2 - NCAA 2005
360 - Fight Night Round 4