I would lean towards photorealistic, while some games, I would say, have used more stylized graphics to great effect, for most games, I tend to prefer slightly more realistic graphics over more cartoonish ones, and I would say the Elder Scrolls is one of those games. But when I say realistic, I mean only in the style of graphics. For example, human characters should look like real people, they shouldn't have absurd proportions and what not, but the graphic designs don't necessarily need to be realistic. I would like something like Morrowind, a style that looks plausible, but with designs that still have a fantasy-ish look to them.
None of you thought Shivering Isles was artsy? What about Halo Reach? That was pretty artsy? Brink is too.
I would not say that really qualifies as what Shivering Isles is portraying is things that don't exist in real life at all. It might not entirely qualify as "realisitic", but this is not because of being incredably stylized, but simply because it depicts a setting that is very different from real life. I can't speak for Halo Reach, though, as I've never played a Halo game before.
For those who plan on playing with dated PC's and consoles at least a hybrid of artsy and realistic is your best bet. Going for realistic graphics on dated tech generally looks terrible. Id rather have something like Oblivion. Slightly sytleized but still realistic to a degree. Helps the game age better too.
It is true that more stylized graphics tend to not look as ugly, when they become dated, as a whole, as more realistic ones. But considering that Bethesda has always tried to make games that are, at the time of release, considered quite graphically impressive, I'm not sure if Bethesda is too concerned with that.