I bought the Surly. The biggest advantage for me was the single-speedability, but I also didn't care for the discs on the La Cruz. They're heavier, and they make fenders and racks more difficult to install. The CC also has a snazzier fork: I much prefer its lugged fork vs. the generic unicrown on the La Cruz.
The La Cruz is made with better tubing, but it's only nominally lighter (the frame and fork together are less than 0.2 pounds lighter than the CC), and that will quickly be erased when you add in heavier disc wheels and discs.
I do like the sloping top tube and longer head tube on the La Cruz, but not enough to choose it over the Surly.
Finally, if you like the La Cruz, buy it soon as I hear it's going away for 2010.
Here's my CC:
