If you are into portraits and landscape Nikon all the way.
Well it is not the camera itself that is important it is the lenses. Both have a tremendous collection
of lenses but for portraits and landscape Nikon is better cut. Buy a cheap camera body but never buy bad lens. But again the camera that you want to buy will not play well with some of the lenses
regarding auto focus. Canon has no such problems. Anyway cameras like nikon D80 and D200 are really cheap these days if you buy a used one and they are very fine cameras. My advice is buy a decent second hand body and invest into great lens, you will be really happy with results. Besides if you dont get good results you cant blame the camera on that:) after all its the photographer who makes the pics not the camera.

Great nikon lens for landscapes:
Nikon 50mm f1.4 or f1.8 (Cheap but REALLY good)
rest are in the expensive side
Nikon 17-55 f2.8
Nikon 14-24 f2.8 (The ultimate landscape lens)

Portraits
Again 50mm f.14
85mm f1.8 f1.4
135mm f2.0

Well most of the lens are really expensive but you cant go wrong if you start with either of
50mm lens which you can get from $120-200.