I don't quite have an answer to the question, but I'll say that the original Sonic the Hedgehog was very attractive in terms of art style, and I think still looks good today. Also, while not exactly graphical features, the ability to look up and down and have the camera move to reveal more of the level was a cool features, as was Sonic's foot tapping when you didn't move him for a few seconds.

Crysis was meant to be that. It was the best looking game on a technical level for a good 4 years. Crysis 3 also looks like it could have come out in 2017 instead of 2013, if going by the PC version.

Rogue Leader blew everything away in 2001. It could have been an early 360 game and no one would have complained.

Half Life 2 and Doom 3 basically set the standard for what to expect from the 7th gen several years ahead of time.

Battlefield 3 set such a high standard in 2011 that the PS4 and XB1's graphics were disappointing in 2013.

Soul Edge/Soul Calibur
Dragon's Lair
Myst
Far Cry (found it much more impressive than Crysis at their respective time of release)

Also, Nintendo trying out different Art styles which hold up very much better than going for the prevalent (then just like now) hunt for more realism, like Wax colors (Yoshi's Island 2), Cel Shading (Wind Waker), Wool (Kirby's Epic Yarn, Yoshi's Whooly World) and so on.

I remember Donkey Kong blew me away, also God of War 3 on Ps3 was the same

That intro on top of the Titan and fighting Poseidon was just jaw dropping

Many games i've seen were pushed hard to the limit up a heard of time in graphics term starting from NES era to early 7th gen era.

-Dead or Alive 3 and Ninja Gaiden (2004) looked realistic for an Original Xbox
-Star Fox Adventures and Conker's Live! & Reloaded had interesting environments and fur effects
-Sega Arcade games and PC games in between 1996 to 1998 were 6th gen ahead before the king of console market reveals PS2
-Mario is Missing & Mario's Time Machine NES version, i describe those games. xD

I think Dead or Alive 2 looked better than Soul Calibur. Better looking and had some great early gen cloth physics.

Virtua Fighter 5. That came out in 2006 and when it was semi ported to PS4 through Yakuza but now in 1080P. I was blown away that the game could pass off as a PS4 game.  Virtua Fighter 5 is the best looking 3D fighter of the 7th gen easily.

Final Fantasy XII looked amazing for a PS2 game.

Heart of darkness. I always thought that was a ps2 game, but it's psx.

Another world was mind blowing at the time.

The original prince of persia, the animations were so smooth.

Starfox Adventures

It was the second cel shaded game fear effect appeared in Feb and JSR in june.