WWW to non-WWW? Choosing the Best Redirections
Many people wonder whether they should choose the www or non-www version of a page as the canonical. While there is significant controversy, this decision does not appear to make a difference in SEO provided you follow a few guidelines. First, it is best to have only one version of each page and 301 redirect to the other. Second, you should keep which one you use consistent throughout a website. In other words, make the canonical files all www or all non-www.