As a neophyte photography student in the 80's, I shot in high school with a silver Pentax K-1000...lots of the students did. They were very pedestrian...we could check them out, shoot our project, and check them back in. Our advisor, the photography teacher, had a black Nikon FE2 on a shelf over his desk...nobody was allowed to touch it. As you approached his desk, I could swear I heard angels weeping and trumpets blaring from that camera!! That made quite an impression on an impressionable teenager.
I think rarity makes something cool. I also feel that product placement makes things cool. Nikons were fewer in number, and the ones I saw were always black. Very cool. Saw them in movies...very cool. "Grab my Nikon" seemed like something a pro would say...not "grab my Canon."
So, in the film days, Nikon was the "it" SLR. Things change. I think in the digital world, I feel like Canon is associated with professional shooters. I see those white Canon banners at tennis matches, on the sidelines at football games and at the Olympic games. Open up National Geographic...my go-to inspirational magazine for travel photojournalism...and there's usually a Canon ad near the front. Perception is reality. I've owned both, and in fact owned film and digital Leicas, and medium format gear. When the rubber meets the road and I HAVE to get my picture, I reach for the Canon gear, an EOS 1DX now.
I'm pretty sure the guys on the ground during the apocalypse will be uplinking images shot with Canon digital gear. So I think Nikon was cool for film, but Canon is cool for digital.