Consider:
Security
What’s appropriate to your requirements? Visual ID, watermarks, digital shredding, threat benchmarking?
Durability
If it’s a magnetic stripe card, how many times is it going to be swiped each day? Will the card be exposed to extremes of temperatures? Will it be used outside? How essential is the quality of print /image?
Speed and volume
Do you need to print single cards ad-hoc and on demand or are you looking for regular large batch prints? Do they need to be single or double-sided? Are you printing in colour or monochrome? How important is print quality?
Scalability
Do you foresee an increase in volume as your organisation grows? Do you want the option to add functionality or remove it as needs change at different times of the year? Will you need to issue different levels of security to different sections of your workforce?