The Top Flite Green box Nobler is actually the one that most folks built in the late 50's and beyond. In my opinion it's a better flier and much easier to trim than the Brodak Original Nobler. It has a slightly thicker airfoil than the original Nobler or the 52 (Man Plan) Nobler, and a lot less asymmetry in the wing. The Original Nobler as kitted by Brodak may be the Original but with nearly 3 inches of asymmetry it is not the best.
Over the years I have built and flown two 52' Noblers, four 57 (Green Box) Noblers, and three Geiseke Noblers. The latter being the easiest to build and the best flying. All are Classic legal and the 52' is Old Time legal as well!
I have also owned one ARF Nobler (sorta 57) and flown more than half dozen of OP's. The ARF by the way is typically light and straight and with small mods a very good flier!
The Geiseke has the best airfoil, the best construction and will typically build the lightest, all things equal. The RSM Kit is a 57 and is probably the best option for competition with a Nobler today, aside from the Geiseke!
My last Nobler was a Geiseke built from a kit about 4 years ago from the Moon Brothers, weighed 37 oz with an Aerotiger and was the best Nobler I've had or flown. It was more than competitive with anything in Classic and would carry it's weight in PAMPA in the right hands!
Some of that was no doubt due to the perfectly running powerplant from Randy Smith.
Randy Cuberly