Multifunction machines can save you money because you end up buying one piece of hardware instead of three or four. But the quality of each individual element rarely rivals that of individual components. If printing and copying are your primary needs, most MFPs will probably suffice. But if you frequently scan and fax documents as well, you might be better off purchasing each component separately. You should also consider who typically views your printed material. If you primarily print for in-house purposes, a good laser printer with scanning and fax capabilities should meet your needs. But if you frequently scan or print photographs or PDF files to send to clients, quality laser and inkjet printers offer higher resolutions and more reliability than most all-in-ones.
For more on printers, be sure to read Choosing the Right Office Printer.