Depends on the purpose of the domain. If I'm doing business stuff, then I usually grab a .com extension, however if I'm setting up multiple sites aimed strictly at SEO and online clicks, then I pick up a .biz, .pro or .info as I can grab them for less than $3.. then rank the heck out of them and beat anyone with a .com name
I don't think I have a favorite domain name extension, I just trust some of them more than others although at this point everyone and his dog can buy a domain name so these trust issues are irrelevant.