Every now and then when I'm reading something, the writer will use a turn of phrase, a specific word, a metaphor, etc, that is unusually clever, or allows me to see the concept in some obtuse light. Or even, they are just able to choose the right words to make something sound musical or rhythmic in some pleasant way. It's intellectually delightful to come across these in writing.
I've never been surprised at AI writing. Emotion the biggest part of communication and these grey boxes have none.