In no particular order
All Time.
LoZ: Majoras Mask: The fact that people are still doing playthroughs, theorycrafting, remixing the music and pretty much everything else from this game(also wicked time was had playing this game) makes it one of my favorite games.
World of Warcraft: I am not going to spout any nonsense about expansion ruining the game or anything like that. Because no matter any changes that I've not liked, it will not change my opinion that World of Warcraft was a unique experience for me and an awesome journey that I had from playing the game with friends I made from this game. This game holds a special place in my heart for doing that.
Pokemon Ruby: I was already a fan of the series before this game came out. I already knew about most of the pokemons from the cartoon and the movies before I played Gen 1 and 2. I had absolutely no idea that gen 3 existed before I saw a copy of this game on a shelf during cristmas. I knew nothing about the game, but I already knew that I was going to have a blast before playing this game. And I loved how the artstyle of the pokemons were different from the previous games. For me, this game marks a point in my life that I will never forget.
Xenoblade Chronicles: I had to wait 6 long, painful years for a console jrpg. The Jrpg lover inside me screamed and wailed from hunger. This game satisfied the lover inside me and ended the pain.
Unknown fifth game: I honestly can not choose a fifth game. Lets just say that I am waiting for it.
This Gen:
Mario Galaxy 1 and 2
Bastion
Pokemon Gen 4 and 5
Monster Hunter Tri
Darksiders 2
Captcha: fellow traveller
Yes captcha, it has been quite a journey.