It just depends on the domain and its purpose.  I like .orgs for sites that are vaugely "org-y" (hehehehe, heehehehehhe, orgy.)  I picked up a .org on which to build a site about a particular kind of addiction.   It makes sense in that kind of context.    
I pick up .nets only rarely, but not out of any prejudice I have against the domain -- despite years of alternate TLDs out there, and the rise of the domain hack, the general internet using public still "thinks in .com terms" so generally, I avoid .nets that are not keyword matches or otherwise have some kind of tie-in reason (for example, if I'm looking at a site that will be called the [whatever] network, then [whatever].net works well.  I also like things that rhyme with "net" for .net domains, but this is by definition a pretty rare occurrence for me.)  
Frank