That's an obvious one though. What kind of wacky ideas have you had for this kind of data?
Another source of data is articles where people comment. You could also do ML to analyze whether the comments are positive or negative, guess the commenter’s age and demographic, etc.
If someone comments on a particular topic, especially if it’s not as popular, it shows they’re interested in the topic. Maybe look at the writing styles and content of people interested in certain topics. Are people interested in X topic more likely to be negative? etc
I don't favorite submissions (or at least, I haven't yet), so I dunno if that would be useful. Very sparse data eitherway.