Recently did this very topic for my website, after seeing it here... Realizedo I should come back and post it here.
I went back through my pocket dumps, and knife pic posts from the last year.
Thankfully I didn't do a LOT of individual posts this year, and already had them in monthly posts! Took long enough as it was!
Counted these the most. No I don't have actual numbers... I'm not that dedicated.

Also have no idea what most Used knife is, since carry and use different from day to day, week to week, job to job, etc.
The Case red bone '44 stockman, and the Case Carhartt Peanut are Honerable mentions; The peanut the most carried of the three I have, and carried by itself quite a lot.
The stockman while not in a lot of the photos, is the knife I remember the 2nd most from this year!
Next up, these two tie for 3rd place, the vintage Schrade stockman being carried a lot early and mid in the year, the Case medium stockman mid and late.
Now, onto 2nd and 1st places.
These two were also close in their appearances, 2nd going to the blue bone Case Modified Muskrat.
But without a doubt, my most carried knife for 2017 was this Case black delrin small jack knife, that I got in a giveaway
@Gary W. Graley did here in the spring.
I do remember carrying and using this one a LOT too. It's definitely become a favorite!
For 2018, I'm going to try for a more accurate/official record of carry, see if we can have actual numbers of days at the end of the year. (IF I can find an easy way to track it!)