Very tricky choice, I really like both (and have looked at both thinking 'I need to buy that'). Have you worn either? Try them on and see what looks right on your wrist, and works best for you.
For example, I had planned to buy a carrera as a dress watch, but actually my full black aquaracer goes with my current uniform of jeans/polo/tee a lot better and I dont know how much wear a dress watch would get. I still plan on buying a Jack 80/81 as soon as I can raise the funds, because I love the classic look, but day to day, probably a Heuer-01 would work better.
The glassbox is one of my favorite designs, but I have a feeling I wouldn't love it so much if I put it on. Who knows, maybe I'd love it more...