I voted, but really, whichever you like better. They are all very good, but they have different ways of shifting, they have different ergonomics and different styling. Different individuals have different tastes. If you can afford to buy and maintain components WAY beyond what you could possibly need, then go for it. I'm happy at the 105 to Ultegra / Rival to Force / Centaur to Athena level myself. Tiagra and Veloce are also perfectly good components and even lower levels work very well.

Only top level pros really "need" the top end stuff and their choices are usually made by their sponsors. For most of us it is more about what we can afford and what status level we are comfortable with.