This is a question that is always asked, the long and short of it is there is such a thing as the correct heating element to use for the the application.
First of all determine what is actually needed to be heated. Sometimes only a part of a tool is required to be heated therefore instead of heating all of it you should employ zone heating. This is of course a cost effective as less energy is used heating necessary parts.
Determine the required temperature and how quickly realistically you need it to get to that temperature. Remember if you require rapid heating then you will likely find it harder to control at the required temperature so it would be recommended to use a PID temperature controller.
Determine the number of elements required depending on the zone to be heated, there will be a formulae for each type of heater to work this out, e.g (cartridge heaters require a 3 times diameter spacing). If you do not have the correct quantity of elements it would make the heat distribution un-even un-controllable.