get what works for you and screw brand loyalty. they are just tools.
I switched after the 5DmkIII failed to live up to expectations of a landscape/portrait/studio dream camera that is predecessor was. In my case the D800 was an easy choice although having owned it for a year now, makes me wish they would scale up their 24MP APS-C sensor into a 50+MP full framer. As the benefits of oversampling will become a key factor for buyers in DSLRs of the future. Nikon could have had an even bigger home run.
The Nikon lens system has also improved very fast to the point where even the 800mm and 100-400 lenses from Nikon make their canon equivalents look out of date. this isn't Nikon from the last decade any more. Therefore, lens wise I'm perfectly happy with Nikon, and they seem to have the right patents in the pipeline to fill even more gaps, namely a 17mm TS. But anyway, back the point, Nikon has the ball for now. that may change, and I may re-evaluate cameras in 3 years when the 5Dmk4 and D900 are out. But for now, and for my purposes, I'm all set. Canon is seem set on chasing the high ISO game of the late 2000's. That's fine for some, but I shoot light, not darkness, which is the lack of light.
And lets be honest, I spend a lot of money getting to location, hauling gear, waiting for the light to be just right and then snapping the shot. Why on earth would I settle for 22MP canon sensors? If anything, I wish somebody would start bringing the medium format digital market down in price to have 80MP+. Every moment in landscape and wildlife photography happens only once. I want to capture it with the best sensor I can afford, and for now that is the D800.
For compact, I've ditched Nikon/canon and I've gone m4/3. the EOS-M is a non event and all the good action is happening with m4/3 outside of the canon/Nikon duopoly.
I'm loving what sony is doing. they are very distruptive and heck they should buy Nikon for all their glass. The point being, stop being the victims of Stockholm syndrome guys. shoot with what works for you. The world has changed. we got options other than canon and thank god for that! nothing sucked more in the last decade than being hostage to one company.