Moving on from Canon... Choosing between Sony NEX, D600 or the new D5200?

Managed to break my trusty old Canon workhorse, so it's time to get a new camera. Canon has been trailing behind in sensors, so I'm thinking of getting something with a better sensor. Unfortunately this might also mean investing in new glass

My main criteria are good IQ, good dynamic range in particular, and light weight of the body (might do some quadracopter shooting).

I've narrowed it down to these 3. Any comments would be most appreciated from users

1) Sony NEX (either 5N or 5R, doesn't make much difference to me. 6
doesn't offer much above the 5 and weighs more?)

-pros: cheap, good IQ, small, super lightweight (280g), possible to use some of my old Canon glass with adapters like the new Metabones Speed Booster (or a cheapo adapter). Has anyone used a Canon mount Tokina 11-16mm with NEX?

-cons: is the IQ really good enough compared to DSLRs?

2) Nikon D600

-pros: great dynamic range, full frame

-cons: price and weight - is the IQ drastically better than NEX or D5200?

3) Nikon D5200
-pros: lightweight (500g), great dynamic range. Wondering how this compares to the D600 generally?

-cons: not sure about DX glass as a future proof investment..