Generally each technology has its pros and cons:
- Mechanical sensors are the least expensive but their subject to environmental conditions and generally fail earlier than the other technologies.
- Inductive sensors sense changes in inductance and capacitance to determine a given level. These are probably the most expensive.
- Hall and electronic sensors do a good job, but both need extra circuitry. So the initial investment of the sensor needs to be evaluated in conjunction with the other circuitry to determine the total cost. Also they draw power continuously, and they can be sensitive to some environmental extremes.
- The reed sensor requires no extra circuitry and uses no power in its off state. The designs are very flexible and because the reed switch is hermetically sealed they can be used in almost any harsh environment.