You should first decide exactly what kind of bike you really want, not a choice of 4 different types. If you decide you want a bike with 700c tires, fine. Disc brakes, fine. Capability of fitting larger or smaller tires, fine. Flat bars, fine, road capable gearing, fine...... then start looking at those.

Also keep tabs on places like Performance Bicycle. You can get some killer deals from them, at very competitive prices, and even get 10% back in store money(you have to join their club first, but that's OK.)

Once you really know what kind of bike you want, also start visiting your local dealers, so they can present their offerings, and give you a better idea of what you are actually looking for.