I've only played Wind-Waker, but from the art-style alone i'd put Okami over Wind-Waker, it just simply looks gorgeous. Not that Wind-Waker doesn't, but Okami simply looks a lot more striking to me.

They both look great but I think Okami shines through. Playing it on PS4 and the game is a literal work of art.

Without a doubt Wind Waker.

Okami for me, I recently platinumed the game and I still amazes me, can't think of any other ps2 game especially for it's length that is better.

Okami was also the only game that we bought each a version of the game on the same day =p.

Both.

Both games will still look stunning in 20 years time.

I think they're tied.

I want to say that, even though I love Twilight Princess, I wish it had a more stylized/cartoonish art-style.

I played the whole thing on my Wii U last year. Even after twenty hours I still found the bloom a bit jarring in places. 9/10 game though. Would recommend to anyone that hasn't played it. 

not to say Okami is bad but i prefer the calmer aesthetic of Wind Waker

Considering WW HD is on Wii U and Okami HD on PS4, WW would hold up even better on PS4.

I think Wind Waker and Super Mario world are the games that aged the better. Less realist graphics the better for longterm.

Okami looks fantastic tho but i feel like the HD version wasn't adding up much conpared to the HD version of WW