From back in the day, definitely SWOS and GP3 will be game experiences I'll never have again and are probably my '10s' from that era.
Moving forward, ISS Deluxe on SNES, Mario Kart and some of the WWF/WCW games of the era were amazing.
PES6 is probably the last '10' for me in terms of fun factor and hours played and with that probably died the last '10' game I'll ever play.
GTAV is a '10' in terms of what it is. Incredible game, but I've neither put the hours in, nor has it grabbed me by the balls like the games above did. Last of Us Remastered is looking like it will be up there too.
Technically incredible era defining games.