I agree with Brett and PJ that the Gieseke Nobler is probably the best, performance wise, but the "nostalgia", and significance, of the Green Box makes it my personal favorite.
Probably my real favorite of the "Noblers" is Mr. Louis Grondal's AMA Special. Built from a Green Box kit and winner of the first two official FAI World Championships! Interestingly he actually used a stock Nobler to fly the two "FAI" rounds and the "Special" to fly the "AMA" round, hence his name for it. (yes, both patterns were flown at the 1960 WCs)
Big Bear