I struggle to choose one specific favourite. Every time I try, the internal monologue sort of goes "yeah, Final Fantasy 8... although FF9 was just as good... but then, Super Mario 64... but what about Oblivion... or there's Fallout 3... Tony Hawk's Pro Skater 2 was pretty important for more than just gaming reasons..." and it pretty much never ends.
So, going by UK release dates, since that's where I'm from: 11 years, 10 years next month, just short of 14 years, just short of 5 years, 2 years, 10 years.