Best by what measure? Best avoided, in all probability, since there are plenty of decent cartridge bearing headsets. While loose balls are the best design, they're also uncommon so you end up compromising and making the best the enemy of the good.
Rat, was hoping to find something that I can quickly repack with fresh bearing and grease that can be brought from next to nothing as oppose to cartirdge bearing like my 1" threaded headset (admittedly isn't that expensive).
Best cup and cone 1 1/8 threadless headset?