I think there's two art directions that really appeal to me at an aesthetic level - a) the stylized, 'painted' or cel-shaded look and b) the semi-photorealistic, 'gritty' look.
For each of these it's a toss up between posting the pioneers in the field and the latest and greatest variants that certainly build on ground-breaking originals. For the 'stylized' camp, I think 'Flashback' & 'Out of this World' are 2D pioneers and Wind Waker is one of the 3D pioneers, but recent entries like Rime look amazing. I hope to see this generation continue to push the boundaries of the stylized game look, utilizing all the multi-teraflop capabilities of current hardware, since most of the focus seems to be on 'realistic'. I dig the 2D / 2.5D look of what Vanillaware and their ilk can do as well, but they sometimes tend to be a little jarring in motion.
In the gritty camp, I think / hope that Naughty Dog will blow us away with their next PS4 game.