Best is such a subjective term. Danny had an outstanding 2007-08 campaign as GM; the near future will tell us if he is still on a roll, so to speak.
It's hard for me to say that Jerry West was outstanding as a GM as well; he had built in assets (LA, money, etc) to help him with his job, and he took advantage of those.
Same with the Knicks. Donnie Walsh might be the closest thing to a second coming for them; but I cannot anoint him as a outstanding GM simply because of the same things that LA has available.
I'd say the best GM is someone that performs yearly miracles in a "small" market..without the financial advantages that LA, NY offer.
RC Buford....I believe has to be considered.
I think Kevin Pritchard is doing a fine job in Portland.