Depends what you want the site for, for example:
For seo sites i tend to either use .COM/.NET/.ORG
But since i have started the affiliate marketing where i use pay per click i buy .INFO domains as there cheap and dont need to be ranking in search engines.
I get my .info's from godaddy as they are something like $1.21 for the year.
I got all my other domains from name cheap because it used to be cheap but i havent bought one in a while so might be out dated and available elsewhere cheaper