If you run large print jobs that you cannot always supervise, you should check the paper-tray capacity of the printer as well as the speed with which it processes, expressed in terms of pages per minute. Be sure the printer is tough enough for your usage by checking the number of images per month it is designed to process.
Also, if you plan to print more than just paper and envelopes, check to see if the printer accepts media such as banners, greeting cards, magnet sheets, or iron-on transfer sheets. Can the copier use legal-sized paper as well as letter-sized?
Don’t overlook some common-sense issues in making your printer selection. If you have limited space and need a machine with specific dimensions, be sure your the machine is sized appropriately. Double check what kind of connection the printer requires–USB, high-speed USB, Ethernet, etc–to prevent nasty surprises when you try to set it up.
If you are still dithering between models, consider the manufacturer’s warranty and the price of the printer. All other factors being equal, choose the unit with the best warranty and the lowest price.