I have shot entire magazine articles with an iPhone just for the unique look ( sharp, great color and lively depth of field ) and in contrast I did an article for the New York Times on Saturday, used a Leica M digital with a 35mm 1.4 and a Nikon D750 with an 85mm 1.8, so it really boils down to the task at hand and the look you want.
For landscapes I am generally shooting black and white film on medium or large format but if I need to do color, I use a Nikon D810 or better yet, a Hasselblad CFV50c digital back.
If you do happen to go the non-SLR route and get one of many enticing affordable compact cameras with the built in lens, just consider battery life, they are often not too great where as a lot of Canon and Nikon SLRs with interchangeable lenses are usually excellent in that regard.
Also, a plug for Nikon.....the system is huge and since it is still based on a lens mount dating back to 1959, there are a
TON of great lenses to be had for it new and used. I routinely use cheap to find lenses like the 28mm 2.0 and 105mm 2.5 on the D810 to great effect.
So based on what you have described, I would get a Nikon D750, remote release and the vertical grip. Then for lenses I would get the 24-120 F4 VR and a 28mm 1.8 for the aurora shots. I'd wait to see what you like on the long end for wildlife since that is where the price and weight can add up fast. When it comes to wildlife, I don't do very much of it but when I do, it is usually in the range of 50-100mm since much longer than that and you are just making another one of billions of "mug shots" of said animal with no real narrative or context, why add to that mediocrity, right?
To understand what I mean about the latter, check out the work of Frans Lanting, Jim Brandenburg or my good friend Michael Nichols, lots of wide angle to normal shots.
Tons of beta out there, lots of hype from the internet gear review star set so brace your self for that...and good luck...
