Why Choose A Freelance Designer?
One of the main advantages of choosing a freelance web site designer over a large corporation is cost. Many freelance designers work independantly, and often from a home-office. This means a freelancer will have little to no overhead costs, where a large web design company will have offices premises, staff, rents and utilities to pay out - this often results in much higher hourly rate than a freelance web designer.
Many corporations also outsource work directly to freelance designers too. This can cause communication delays when your point of contact doesn't have the technical skills necessary to answer your questions. You're better of working directly with the designer on a web design project.