What kind of printing do you intend to do? If you plan to print large volumes of black-and-white text, the extra speed and low per-page costs of a laser all-in-one printer may justify its higher initial price. If you want to print photos or color graphics, however, you'll get better results from an inkjet all-in-one printer -- especially one with more than four ink colors. If you want to print photos directly from a camera, look for a good-sized LCD preview screen, memory card slots and PictBridge capability.
How much desk space do you have? All-in-one printers take up more desk real estate than regular inkjet printers (though the difference between the two is shrinking). However, they still use much less desk space than separate devices would. Be sure to also consider things like automatic document feeders and needed clearances for trays and output if things are tight.
How will you be hooking up your all-in-one printer? Many multifunction printers have Ethernet ports for wired networking, and some also have wireless networking capabilities. Not all printers are network-ready. An all-in-one printer without networking can still be shared, but only if the computer it's connected to is left on. Some newer all-in-one printers can connect directly to the web without being hooked up to a computer.
Do you need high-capacity paper trays? If you do a high volume of printing, you should get a printer with high-capacity input and output trays or drawers to save yourself from constantly reloading paper. Some manufacturers sell high-capacity paper trays as an option for certain multifunction printers.
Do you need duplex printing? This is a time-saving convenience that allows automatic printing on both sides of a sheet of paper. Duplexing, though essential in a busy office, may not be worth the additional expense to home users, who can do it manually by printing odd pages first, then flipping the stack over and printing even pages. Keep in mind that using a duplexer often increases print times significantly.
What type of copying and scanning features do you need? If you plan to copy multipage documents on a regular basis, an automatic document feeder (ADF) is a must. If you'll need to scan frequently, one-button scanning is a useful feature. With this feature, you place an item on the scanner and push a button, and the scan is saved to your computer. Most all-in-one printers include scanners that are good enough for general-purpose use, but for ultra-high-quality photo scans, you may require a separate scanner.