Who has already ordered either one? What camera will it be replacing? What lenses do you plan to use it with?
As for me, I ordered a A7R, to replace a NEX 7. I plan to use it with a Touit 12mm in crop mode, a Leica Elmar 24mm f:3.8 (fingers crossed), a Zeiss FE 35mm f:2.8 (also on order), a Leica Summilux 50mm f:1.4, and either a Leica Summicron 75APO, or a 90mm APO depending on availablity.