I see a fairly even split here but possibly 2-1 in canons favour, although sometimes all I'll see are Nikons, on another day it's almost all canon. In the past 5 years I've seen a lot more Nikon advertisements, specifically the "I am Nikon" adds which were a common sight for a while.
I chose Nikon as my housemate shot Nikon and I'd borrowed his camera quite a bit and liked it. It also seemed that most online comparisons and youtube videos suggested the D3200 was the best beginner camera with its guide mode thingamejibber. I never used that anyway though.
If I was starting from scratch now, I'd be seriously tempted by the 7DII for wildlife with its faster frame rate and bigger buffer but I'd have to do some head scratching between that and a D7200.