90s- Spyro 3
00s- Lost Odyssey
10s- Persona 4 Golden

I'll stick to decades from which I've played many games.

80's - The Legend of Zelda
90's - Super Metroid (GOAT as well) 
00's - Half Life 2 / Metroid Prime tie
10's - Xenoblade Chronicles

2000's
Fire Emblem Radiant Dawn

2010's
Xenoblade Chronicles (Will probably change to Xenoblade Chronicles X, SMT x FE or Fire Emblem If in the future)

80's Super Mario Bros 3
90's Pokemon Red/Blue
00's Paper Mario
10's Pokemon X/Y

70's - Pong
80's - Punch-Out!!
90's - Super Mario World
00's - Super Smash Bros. Melee
10's - The Binding of Isaac: Rebirth

In my limited experience, I'll go with:

80s - The Legend of Zelda
90s - Chrono Trigger
00s - Metroid Prime
10s - The Last of Us

80s - Super Mario Bros. 3

90s - Super Mario World 2: Yoshi's Island

2000s - Hum... Honestly, I don't know... Super Smash Bros. Brawl?

2010s - Alan Wake

70's: Galaxian

80's: Space Harrier

90's: NiGHTS into Dreams

2000's: Panzer Dragoon Orta

2010's: Bayonetta 2 (so far)

80s: Super Mario Bros. 2
90s: Banjo-Kazooie
00s: The Legend of Zelda: Wind Waker (my overall #1)
10s: The Legend of Zelda: Skyward Sword

I am only going to do the decades that I have been alive

90s Megaman X
00s Viva Pinate
10s Mount & Blade