The static interference generated will cause data corruption because of the lack of shielding to insulate the data from the static field around the cable. In this case, the cost will go up as your choices are narrowed down to the heavier and harder to work with shielded cable types. If you are installing in the home or in an office building, then UTP is fine. If you are concerned about 'wire tapping' and interception of data on the wire, or where interference is extreme, fiber optic cable is used. Third, you must calculate the overall length of the cable system.
Some types are more resistant to degradation of signal over a long distance than are others.
Fourth, you should give some thought to the municipal building codes. Almost all codes require Plenum cable when it is run through the air space above a hung acoustic tile ceiling in an office building. Put simply, if the cable is installed inside a wall or ceiling, it should be Plenum. Finally, if you are using UTP consider the cable category. Make sure it meets the requirements for the speed of the network you are installing.