Dotcom is KING... but after that is a toss up. I don't care for .nets too much myself. Dotorgs have their place for non-profit groups. Dotbiz seems to me the most desireable for a business name after dotcoms, but they are still not very popular. I talk to people all the time that do not even know .biz or .info exist. I also like .info for some types of sites. I own a couple .info domains for local communities in my area that I am planning on developing. The only problem is it takes a lot more time and money to market a non-dotcom domain, than it does the dotcom version of the same name. People are just more accustomed to remember dotcom versus anything else.
I have a friend that is head of the european marketing department of Henkel company;she didn't even know that something like .net exists.Only extensions familiar to her were .com and specific cc's like .de.Seems like the "enduser" really is only aware of .com.
generally, IMO .net's the best of the bunch, exceptions being .org's and .info's that describe an organization's goals to a tee. For instance, it would be much better for a Green organization to have SaveTheTrees.org than SaveTheTrees.net.