Low Speed  High Torque
Servo Motor： Servo motors will do fine with low speed applications given low friction and the correct gear ratio
Stepper Motor： Stepper motors provide most torque at low speed (RPM).

High speed High Torque
Servo Motor： Servo motors maintain their rated torque to about 90% of their no load RPM.
Stepper Motor： Stepper motors lose up to 80% of their maximum torque at 90% of their maximum RPM.

Repeatability
Servo Motor： Servo motors can have very good repeatability if setup correctly. The encoder quality can also play into repeatability.
Stepper Motor：Because of the way stepper motors are constructed and operate they have very good repeatability with little or no tuning required.

Overload Safety
Servo Motor：Servo motors may malfunction if overloaded mechanically.
Stepper Motor：Stepper motors are unlikely to be damages by mechanical overload.
 

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.

Frame Sizes
Servo Motor：Servo motors are availible in a wide variety of frame sizes, from small to large motors capable of running huge machines. Many of the motors come in NEMA standard sized.
Stepper Motor：Stepper motors do not have as many size selections as servo motors in the large sizes. However stepper motors may still be found in a variety of NEMA frame sizes.

Motor Life
Servo Motor：The brushes on servo motors must be replaced every 2000 hours of operation. Also encoders may need replacing.
Stepper Motor：The bearing on stepper motors are the only wearing parts. That gives stepper motors a slight edge on life.

Setup Complexity
Servo Motor：Servo motors require tuning of the (PID) closed loop variable circuit to obtain correct motor function.
Stepper Motor：Stepper motors are almost plug-and-play. They require only the motor wires to be wired to the stepper motor driver.