Canon 5D Mark III vs Nikon D800 - Hands-on

Both Canon and Nikon have both released their successors to the 5D Mark II and D700: the Mark III and D800. Which one is the better full frame DSLR?

Nikon D800 pricing reference: http://www.digitalrev.com/product/nikon-d800-dslr-body/MTAwMDI5OA_A_A

Canon 5D Mark III pricing reference: http://www.digitalrev.com/product/canon-eos-5d-mark-iii/MTAwMDQwNQ_A_A