for SEO anything except for .info the .us or .com or .net .org is ok for seo same, for the USA the best is .com and .us then for high competition high content comp use .org for value of resell only .com 99% of the time.
My advice (and I'm trying to be unbiased since I specialize in dot us domains) get the best keywords possible. Whats better? SEOAdvice.us or SEOAdviceFromMe2U.com
as others said before, choose .com if at all possible, then .net or .org. Anything else needs more work regarding SEO AND you migh not be able to sell it easily if selling is part of the plan.