Jhon,
I second James' questions. If you're starting from scratch with no camera bodies or investment in lenses/flashes/accessories, etc., then it's a question of budget with all of those things added in. If you're starting a business, do you also have everything you need for processing those images: computer(s), software, etc. Nikon has some great cameras -- both full-frame and crop bodies -- so it's really a question of budget and whether beyond weddings you have other photographic needs that the cameras/lenses will have to fulfill -- like sports, nature, events, landscape, etc.

Jim