make some scale on each web design company,and finally choose a best one which can meet your expectation.While scaling please do remember some tips.
1.Observe the some of the projects which were handled by the company
2. had a chat with the employees of the company,this is really helpful to know the expertise of the employee.
3.Discuss about your site with the designer before going to start. and many more.
These would really gets you to find a best web design company..Thank you