Re: Nikon D300S Vs canon 7D
Very few people on the forum will have actually used both, especially as they are pretty recent. And what is useful here is having actual experience of the material.
I use the D300. I was delighted when Canon came out with the 7D because it is so similar, even down to the gridlines in the viewfinder by LCD screen. It confirmed the concept of having the choice in mid-range cameras between APS-C (D300s/7D) and 24x36 (D700/5D). And Canon reinforced this direction by bringing out a new APS-C lens to go with the camera (15-85 IS).
If I were you I would go and try them out rather than poring over the technical specifications. These cameras are complex tools and yet you have to be able to master them easily. See which one you feel most at home with in your hands.