Everyone has their favorite games and so do I. Based on my experience and on what I've played, I'll post here, by genre, what my favorite games are. Of course, I'll have to leave many stuff out, but at least I'll let you guys have an idea about my taste.
RPG: Suikoden II
This is probably the hardest choice, having played hundreds and hundreds of RPGs. When I first played Suiko2, I wasn't familiar with the series and though the system and graphics weren't too catchy, but as story progresses, I found myself in love with this gem. Definitely the best story a RPG ever had.
Adventure: Snatcher
Without a doubt, my favorite adventure game ever. Even though I loved Policenauts and Famitan2, this is definitely my top tier. Graphics, music, voices, gameplay, fanservice, this game has it all. A true masterpiece by Hideo Kojima.
Action: Streets of Rage II
Even today, I still prefer 2D beat'em ups to 3D action games, so this is my choice. Streets of Rage II, a game that made my childhood afternoons occupied. The game's flow is just amazing, each stage and character is unique, and Yuzo Koshiro made his best work for this game also.
Fighting: Rival Schools
Another hard choice, specially because I prefer 2D Fighters as a whole. But Rival Schools was one of he first fighting games I played and it will forever remain in my heart as one of the best. Interesting characters, excellent music, fun gameplay and good story mode, this game sure showed me how good fighting games can be.
Strategy: Age of Empires II
Not one of my favourite genres, but this game sure was fun back in the day. Build your empire, occupying territory and conquering the land, this game sure was revolutionary.
Driving: Gran Turismo 3
My first PS2 game and one of the reasons why I love driving today. A driving game couldn't be more realistic back in the early 2000's. A true gem for any car and driving lover.