Please vote—What topic would be best for an investigation and brief post?

Followup to: Systematic Search for Useful Ideas

I’ve set up a pairwise poll for this question and additional suggestions are welcome. My original proposal was to examine topics that haven’t already been covered here, but instead of that, I’d like to ask people to consider the existing level of discussion on a topic in evaluating what would be “best.”

ETA: There are currently over 500 pairs. You don’t have to go through all of them—answer as many or as few as you like.