The very fact that you are asking this question means that the answer is neither. Get an 18-200, use it for a year and then answer your own question. Both are best in class at different jobs. Your question is like "shall I get a car or a helicopter".
I do actually have both lenses sat next to me so I could answer the question if I knew what it was. The 24-70 is going back to my mate because I was just comparing it to my 24-120. The former looked to have the edge in resolution, however the 24-120 is very good and far more versatile for my requirements. If you wanted my 70-200 you'd better bring a gun.