Cost
Servo Motor： The cost for a servo motor and servo motor system is higher than that of a stepper motor system with equal power rating.
Stepper Motor：This feature would have to go to stepper motors. Steppers are generally cheaper than servo motors that have the same power rating.
Versatility
Servo Motor：Servo motors are very versatile in their use for automation and CNC applications.
Stepper Motor： Stepper motors are also very versatile in their use for automation and CNC applications. Because of their simplicity stepper motors may be found on anything from printers to clocks.
Reliability
Servo Motor：This is a toss up because it depends on the environment and how well the motor is protected.
Stepper Motor：The stepper takes this category only because it does not require an encoder which may fail.