Most clients hire photographers for their images and the prompt service they provide, not for the brand of the camera they use. Yet, a few prospect clients sometimes ask me about my photography equipment.
As a photographer I believe the best camera is the one I have at hand, whether is a Canon, a Nikon, or a smartphone. A camera will always be as good as the one who uses it.
In a nutshell, these are the most common items photographers carry in their bag when doing a photo shoot: