Which do you like riding more? The geometries of the two frames are similar, but not exactly the same, so the fit and ride will be a bit different.

Both frames are quality products, as are the groups - I have more than 10,000 miles on an Ultegra Group and more than 10,000 miles on a Sram Red group with no durability issues. And I have a Caad 9, a Specialized Roubaix Elite and Specialized Tarmac frames in my garage right now - though we are trying to sell the Roubaix - so I speak with experience about the fit and quality of the frames.

This is really a can't lose decision. Just go with whichever you like riding more. And if you can't decide that - pick based on frame color.