To a lot of people this is a tough decision.
Consultants enjoy the benefits of owning their own business and are often highly independent.
They typically go from project to project and can often pick what kind of work they'd like to do. They can more easily stay on the cutting edge of technology. Generally, companies hire consultants for one of the two reasons. First, to do work that is highly specialized, that their internal employees don't know how to do. Second, companies hire consultants to do work their internal employees don't want to do.