Phantasy Star Online EP1&2
My first MMORPG, And [The DC one was] the first game I was ever able to create my own character in. Mix in the Great story of the corrupt government hiding shit, finding Rico, and the environments and you've got a bad-ass game for the ages, and I'm not even touching the online aspect (Note: It was awesome, and the best online community I've been a part of yet).
Majora's Mask
This basically just got higher then OoT cause I can actually go back and play this one half-way through.
Ocarina of Time
Best game in my childhood until PSO. Can't go back and play it for more then 30 mins.
Mother 3
Fantastic RPG, I'd even go as far as to call it the best RPG ever.
Final Fantasy 6
Best RPG ever until Mother 3 came along.
Chrono Cross
RPG that I've invested in the most. I.E. reading theories, and stories and such.
Shadow of the Colossus
Best bosses ever.
Halo: Combat Evolved
Best Deathmatch ever.
Gundam Extreme VS.
Best Gundam game ever.