Cost is the primary driver for the SMB space. Other things to consider are to determine if the product is viable in the market, the serviceability and the ease of use, including the implementation and configuration.
Another thing to look for would be the environmental footprint, such as power and heat, and even the rackability of that product. Other key factors to examine would be backup and recovery, the ability to internally tier storage and, of course, scalability.
Check out the entire NAS FAQ guide here.
