In the recent reputation recalculation resulting from weighting question upvotes back to 10 rep instead of 5 rep, some sites on the SE network underwent not only a reshuffle of the reputation leagues but a change in who's the #1 highest-rep user. These included:
Puzzling: I lost the top spot in May but got it back in the big November recalc. (I've posted 200+ questions and Gareth McCaughan none.)
Movies & TV: Paulie D (6 questions) had overtaken Walt (0 questions) this year to be the top user, but then Ankit Sharma (400+ questions) shot to the top in the big November recalc.
How many times did this happen on the whole network? How many sites got a new #1 rep user only due to the question rep change?
The query compares the current situation (+10 reputation per question upvote) with the old one (+5). It does account for the daily reputation cap (except that suggested edits are ignored, but I doubt that would make much of a difference – these users have long reached the point where they can even edit tag wikis). Right now it's pretty accurate since SEDE was updated November 17th, and I've saved the current situation in the Wayback Machine.
The old reputation is kind of a 'virtual' situation, it will continue to count future upvotes with the old rules. So the query will eventually answer something different: which sites would have a different top user if we'd still have the old reputation system?