I don't think AI has good enough taste yet. The best possibility I know of is giving users a higher-signal (than upvoting) way to single out a post that they think is particularly good. This would be like flagging, but for good things rather than bad. Actually, that was our intention when we created the 'favorites' feature and made favorites public—but it didn't work out that way, so maybe this is harder than it sounds.
There's a bit more discussion about this at https://news.ycombinator.com/item?id=23157675.