Not sure how scientifically valid this poll may be but:
https://shotkit.com/camera-survey/
Nikon is No. 1 with pros. Canon No. 2. Sony third.
Nice reading for the Nikon devotees (like me , long time, former pro, retired now Nikon shooter ) but IMO only wishfull thinking
When I got my 1st F2AS and FE in the late 70's , despite Canon's vigorous attacks (which I was kept informed about by a acquaintance who worked at Canon Europe) Nikon was the nr 1 brand, with consequently a wide dealer network, Nikon dedicated third party accessories and wide selection of 2d hand offerings
But that came to an end with the introduction of AF, when Nikon got a (justly so, I hate to admit) beating from Canon due to holding on too long to the slow AF F4. Thanks to the faster and constantly improved AF of eg the EOS 1 and 1n, clver markering (impossible o ignore white lenses) and simply persuading photographers to change brand by making attractive financial deals Canon ruled sports and PJ, and consequently much of the amateurr market.
Nikon seemed to make a comeback with the D1. But when its pro level models too long used noisy DX sensors, Canon soon overcame that too with better high ISO and FX sensors bodies
It only was with the 2008 D3 that Nikon made a serious return, although at best only perhaps on par with Canon
Histry kind of repeated itself with mirrorless, with Nikon just releasing pro level ( the Nikon 1 series really were advanced amateur at best) full frame bodies (DX even later) four years ago,while in particular Sony, as well as Canon had had offerings around for years
Sure , the Z9 by many reviewrs is considered to be at the top of the pinnacle rigt now. But the 'lower' grade bodies like the Z6/Z6II and Z7/Z7II in all honesty (still fondly use my 2018 Z6 alongside my 2021 Z7II) simply trail their competitrs
At the events (catwalk, dance and shoots ) I despite my retirement still drop by to take pictures (can't resist it) Nikon still is the underdog, alongside a lot of Canon's and Sony's
So IMO , 'Nikon most used' a nice thing to dream about, but realy only wishful thinking. Althiough that won't make me switch brands