Everybody has their own experience. I honestly have only sold a couple .net and .org and only had luck with strong keywords, I would not reg anymore unless it was a 3 letter or was a solid term. I have however been selling .info .us I had luck with .biz when I had all the single keywords and have yet to find anymore available so I just don't bother regging garbage names.
My choice would be:
.com
.us
.info
I would not touch a .biz .net or .org unless it had easy wholesale value such as 3 letter combos or generics etc...