I am often asked about drives and motors suitable for Mantis Motion Control so here's some initial responses - you can email me for any more detailed information.
1. What motors and drives can I use with Mantis?
The Mantis controller outputs 8 channels of conventional 5v TTL step and direction for each motor. These signals can be interfaced to a broad spectrum of step motor and servo motor drives. Typically anything used for CNC applications will also work with Mantis.
For general all round use Leadshine DM series drives are hard to beat. They are inexpensive, require minimal setting up, with convenient dip switches to set current and micro-stepping rates. They are very smooth with an excellent anti-resonance feature. They also have opto isolated inputs which is important for protecting your controller in the case of a drive meltdown. They can drive step motors from as small as a fraction of an amp up to 8 amps and at supply voltages from 18 to 80 volts depending on the model.
You can check the range at www.leadshine.com - they have agents around the world and also can be purchased from ebay shops.
An alternative drive if you want something really tiny and even cheaper are UIrobot drives. http://www.uirobot.net These can even be mounted directly on the motor if required. They are not quite as smooth as Leadshine, but do have opto-isolated inputs and a built in heatsink - making them far preferable to other cheap drives like Easydriver etc. They will also work down as low as 10v dc so are suitable for portable battery powered rigs.
If you want to better understand the technical functions of stepper motors in general then check with www.geckodrive.com. They also explain much about the power supply requirements.
2. Are servo motors better?
Not necessarily, in fact they can create more problems because of their intricate tuning needs. Stepper motors provide a broader range of torque - especially at low rpm - hence are easier to use because they do not need such high reduction ratios to drive axes. For example for a track drive you can directly couple a stepper motor to the drive pulley - whereas a servo motor would require a reduction gearbox. Servo's also require more complex wiring and can be more susceptible to interference. For a simple reliable system there is little need to over-complicate your life with extra technology. If however you are a speed freak and want the ultimate performance then servo motors might be an option.
Alternately you can also consider an option like Leadshine Hybrid motors. These are stepper motors with the addition of encoder feedback - so they offer the best of both worlds in terms of high speed, torque range and smoothness. They are also more resistant to loss of position - though this can be a double edged sword. If you hit an obstruction with these motors they will try a lot harder to overcome it before they decide something is wrong and go into fault mode! Whereas a stepper motor will more often just stall and sit there...