I only own one system for digital photography, but it can't be mentioned here . For film though...geez, I don't know how many different brands I shoot. It's a lot. I don't own a Nikon...I do have a nice Canon F-1/A-1 kit. Love my Mamiya RB, Pentacon 6 TL, Omega Rapid 200 and Fujica G690BL. Also have Olympus, Minolta, Pentax, and other 35mm systems...but I don't use them much. Also have a Leica, but I'm not in love with it. For small format, I'd rather shoot an SLR for the most part.
I don't want to go all Stalin on you fair folks going all old school with your film cameras. But i am kinda looking for those wedding photographers here that uses non-Canikon as their primary gear.
So far I think it's Sony by Ricardo with some folks just Leica M9 as supplementary camera.