Some points of contact that might be interesting/insightful:
# of quizzes completed segmented by score (e.g. 1/5, 2/5, ..., 5/5)
user's top 3 most played tag (e.g. Geography, History etc.)
most played quiz or playlist (e.g. Gen. Knowledge, Category Elim. etc.)
Not sure if this has been suggested before (wouldn't shock me).
As premium users (at the beginning of the next year) we get the year before's stats. Such as: Total takes, Average takes per quiz, Average takes per day, Top quizzes (which shows how many takes ALL of your quizzes got (which you can limit with Languages, Types and the number of quizzes you want to see)).
I guess they could add other features though so it's still a good idea!
Maybe the number of plays all of your series got? And I agree with you it would be interesting if we could see stats just for the quizzes we TOOK as well as made.
But maybe I'm getting roped into the "stat-ification" that seems to be spreading like the flu.
1. leaderboard of # quizzes taken
2. leaderboard of point increase per quiz take (some minimum floor of # of takes e.x. 500)
3. streak calendar that illustrates when and how long you streaks lasted
4. AND MY BEST IDEA: like spotify shows you your top artist we could show your most taken quizmaker (excl. the master himself ofc)