There is not a lot of difference between a Nikon to a Cannon. The real difference is the lens, it depends what you can afford, what you are shooting for and where you are shooting.
For the best quality picture go for a fixed lens, or a professional zoom lens. A cheap lens on the best camera in the world with the cheapest lens will produce bad pictures. It's what the camera is looking through that determines the quality of image and the size negative.
A Bronica medium format will always out perform a 35mm camera. If you know how to use it.
