The reason that more of .US and tons of the BIZ 3 letter domains are available than .INFOs, is because their resale value are unproven. However, in another post, Domebase indicated that already, a (Confidential 3-letter acronym).info sold for 11,600 euros!!!!!!!! I think it was at Sedo.
Thus in my opinion, .info is by far the best ââ¬â that is ââ¬â unless you simply need a certain 3 letter acronym and do not care about the extension or resale.
As far as which is the absolute best 3 letters, (eg. chicken parts vs. initials) if you do not tell anyone ââ¬â nah, I am not going to say. I suggest you start maintaining your own database of sales and othersââ¬â¢ desires. In that way you will be able to answer your own question ââ¬â in 3 years.