Mirage or Veloce are going to be the best bang for your buck. If you have a Shimano neutral support, the 9's will generally shift almost flawlessly, while the 10's isn't perfect, it will get you through the race. Campy is not much more expensive than Shimano, and I run 3 roadbikes with Campy, which is why my cross build is also going to be Campy.