Test ride both types of bikes and prioritize what you value most. If you value speed I would probably give the edge to a CX bike. If you value comfort the edge probably to a touring bike. Etc, etc, etc. Of course your opinion may differ after you ride them. Njkayaker made some good points also.

When I went looking for a new bike I took notes. I included factors such as price, location, frame material, wheel size, etc. I also took subjective notes such as speed, quick handling, comfortability, adaptibility, etc. I started looking around August, and ended up buying in December. This after multiple test rides and narrowing down on what I wanted.

You can make your decision any number of ways. And if all else fails, buy the bike with the prettier colors.