My rankings - based on sales
.COM (the winner and still champion)
.ORG (as long as the name suits the extension well)
.NET (VERY tough to sell unless it is a great word/term)
.US (the up and comer that will make big waves in America)
.INFO/.BIZ (depending on what the word or term is)
I expect .US to move up to #2 (in America) within 3 years. I know a lot of people who already take the .US when they have a choice between .US and .NET. Might seem silly now but I think it will look smart in the not too distant future. .NET carries a lot of baggage that .US will never have to deal with.