Which stepper motor should I use?That is a question without any context.Kind of like which piece of furniture should I buy?Is it for the bedroom, dining room or patio?Or do you need it to sit on, store items in, display things or?You need the proper context to give proper answers and motor selection needs to be fundamentally decided on a series of parameters.One motor isn’t suited for every application, and all motors aren’t equal in performance.In general buy an 8 wire motor where possible.An 8 wire motor allows you to wire it to be driven unipolar or bipolar.If possible buy a dual shaft motor.While originally dual shaft motors were designed for an encoder on the other end, a simple knob allows for manual adjustment when the motor is not energized. When comparing motors look at the coil voltage, coil current and coil inductance of a motor.For rapids, lean to motors that have lower coil inductance and coil voltage verses higher values. If you buy a 4 wire motor you have to drive it with a bipolar driver. If you buy a 5 wire motor it has to be driven with a unipolar driver. Both a 6 wire and 8 wire motor allows the flexability to user either a unipolar or bipolar driver. However a 6 wire motor become more problematic to drive bipolar, as if you use the full coil winding, the coil inductance is problem for rapids but it gives you the full rated holding torque of the motor. If you drive it half coil, rapids improve considerably, but you have essentially the equivalent holding power of the unipolar rating.
The below video will show you empirically why lower coil voltages and coil inductance aids rapid performance.