Use the Matchmaker at Gary Fisher. It asks you questions and recommends a bike for you. Trek owns Gary Fisher.

Keep in mind that your cycling habits may change. I personally thought about the comfort bike at first. I am glad I didn't make that mistake. Unless you are convinced that you are going to be on the pavement most of the time, I would go with a Mountain bike.

The tires alone are a reason to stay away from a comfort/hybrid in many cases.