I like how you define it as value over quality. That makes for a much broader range of posts that give value.
I like to think of good value posts as ones that are not using linear abstraction as the mode of thinking, that give an inkling of there being an actual person doing the posting. Okay, so you posted a picture of your dog. Awesome (actually, all posts of dog pictures are awesome because dogs are the best thing ever).
But where are you in this post? What memories does this pic of your dog trigger? I wanna know something more about you, something from your heart, or your gut, or your soul, or your genitals,, or your yearning or your regret, or your mind. That's what's valuable to me - seeing posts that are written by humans, not just slipping one or two categories into a post and pressing "post". Where are you? I wanna see you.