a random sampling of impressive games, technically (graphically) or gameplay-wise:

nes: kirby's adventure (colorful, detailed sprite-based gfx)
snes: yoshi's island (dat art style)
n64: f-zero x (60 fps!)
gc: f-zero gx (60 fps and gorgeous!)
wii: kirby's epic yarn
wii u: yoshi's woolly world (from what i've seen)

SNES and Genesis: Pretty much everything compared to NES.

Saturn: Virtua Fighter 2. It kinda set a benchmark in presentation and gameplay.

PS1: Metal Gear Solid and FFVII

N64: The feel of shooters like Turok and Goldeneye. Which is why shooting fans flocked to N64. The AKI (WWF/WCW) wrestling games also raised the bar in that genre.

Dreamcast: Shenmue, Sonic Adventure, Jet Grind Radio, Dead or Alive 2

PS2: Metal Gear Solid 2 and GTAIII

Gamecube: Mario Sunshine

Xbox: Halo series

Xbox 360: Oblivion, Gears of War, CoD4, Condemned

Fight Night Round 3 was pretty amazing at the time.

I remember the first time I played that game. I wanted to play a match before going to sleep with my gf, but I stayed up all night and pretty much finshed the career mode.

SNES: Earthbound. I remember staying up at 1AM when I was little, preparing for the final boss. While I fought Pokey, I listened to the retro music playing until it suddenly changed into loud jamming, 16bit goodness. I was blown away by that, but what came after was the Giygas fight itself. The eeriness of it made me gasp in awe, and when the alien started going crazy, it was a memory I will never forget.

PSone: Xenogears. The story captured me the moment I played it from beginning to end. The most memorable part to me was when Id tells the tale of Fei's past. The music captured the mode, as did the reveal of Fei's mother being Miang. The final boss (The one on one duel) was another wow moment for me, given the atmosphere.

N64: Ocarina of Time. Ganon fight. Need I say more? :)

Gamecube: Metroid Prime. The only game where the graphics made me gasp in awe. Never have I been impressed with visuals in a game, but this one took the cake. The boss fights were amazing, especially Omega Pirate and the final boss.

Tales of Symhonia: My favorite game of all time. When you have a game that 'makes' you stay up till 5AM playing it. Its the reason why RPGs are my favorite genre of video games today.

PS2: Persona 4. This is the only entry that I didn't play when that generation was sitll going on. In fact, I am playing it right now. It has wowed me numerous times, in particular the dungeons you go through. My favorite would have to be Shadow Rise's though, considering how surprised I was when it appeared. The amount of content in this game is almost countless, and as I continue to play it, the more I regret not playing the game when I had a PS2.

Wii: Xenoblade. The various places you went in this game really made you feel that you were really there. Sometimes, I would just stand in a particular spot and watch it go from day to night, gazing at the environment as it changed. One area that did this the best was Satorl Marsh, and anyone who has played the game knows what I am talking about. The music in that area is amongst the best I have heard, as is the soundtrack as a whole.

PSP: Trails in the Sky/Ys Seven. These games are why I am a hardcore Falcom fan today. Trails in the Sky has some of the best cast of characters you will ever encounter, while Ys Seven's gameplay is truly amazing. Their stories are stellar too.

Nothing has wowed me yet this gen, but that will likely change soon. (Zelda U, Xenoblade X)

PS1: Crash Bandicoot: Warped, Chrono Cross
N64: Banjo Kazooie, Majora's Mask
Dreamcast: Sonic Adventure, Shenmue
PS2: Shadow of the Colossus, Ratchet & Clank: Up Your Arsenal
GameCube: Wind Waker, Metroid Prime, Resident Evil Remake
PS3: The Last of Us, Uncharted 3
Wii: Skyward Sword, Super Mario Galaxy 2, Metroid Prime 3

4th gen: Starfox, Donkey Kong Country 1-3

5th gen: Starfox 64, Banjo Kazooie, Ocarina of Time

6th gen: Rogue Squadron 2, Resident Evil 4, Conker Live & Reloaded, Metroid Prime 1 & 2

7th gen: Mario Galaxy, Bioshock, Bioshock Infinite, Xenoblade

Wow, its good!

PS1: Tenchu Shinobi Taisen, GT1, Einhander

DC: Ikaruga, Jet grind radio

PS2: Bouncer (at launch), GT3, GT4

WII: Fragile dreams

GC: Resident Evil Zero

64: Nothing.

Xbox: Burnout 3, Halo 2, Phantom dust

Xbox 360: RDR, Forza 4, Lost planet

PS4: Destiny beta, Morpheus (tested)

XBO: Sunset Overdrive

WIIU: Erm.. i guess Fatal frame V, but not really.

3DS: Nothing

PS Vita: Nothing

Wow, it's bad!

PS1: Meat shop, any western RPG

DC: Some bus simulator

PS2: Every single kingdom hearts game.

WII: Everything except fragile dreams

GC: Most games

64: Everything

Xbox: Virtually every japanese only game, and a whole bunch of western games

Xbox 360: Most third party games

PS4: Most third party games, and almost all indie games

XBO: Froza 5, Most third party games, and almost all indie games

WIIU: Everything except maybe FFV.

3DS: Everything

PS Vita: Everything

Wow, you went beyond and did a bad list! You have some high standards too. But I love you for mentioning Fragile Dreams and RE0. I loved those games : )

Gen 3: SMB, Zelda II, and Mario 3
Gen 4: Sonic, SMW, F-Zero, then later Star Fox, DKC and Yoshi's Island
Gen 5: Wipeout, Mario 64, TOOT, Banjo Kazooie, Perfect Dark and Conker
Gen 6: Rogue Squadron II, Pikmin, Metroid Prime, GTA III, F-Zero GX, RE4
Gen 7: Mario Galaxy, COD4, Uncharted, Skyrim, GTAV
Gen 8: Nothing yet, although MK8 is very pleasing to the eyes, and Ryse at times looks great.

I just finished playing through BioShock Infinite (for the 3rd time) a few minutes ago. "Wow" is the only word that can be used to describe it.