Best Alignment Protractor?

An old plastic Dennesen Soundtractor. Yeah, the part of the device that extends from the center hole to the tonearm's pivot point broke at some point in the distant past, but it was easy to accurately put it back in working order with a couple windings of Scotch Tape. Luckily, the component broke in such a way that it was a cinch to reassemble it to audiophile tolerances.  To be sure, it's important to wear magnifying glasses and not to drink too much coffee before mounting cartridges as you don't wanna have the shakes, but I've always done damnably accurate work.  Depending on the shape of the stylus, of course, and vinyl pressing vagaries, I  get near flawless tracking from edge to lead out groove with the vast majority of the records I play.

I've hated needle/cartridge mistracking since I was in my single digits. I've always hated spitty sibilants, buzzy vocals & scratchy violin sections.  And don't get me started on hashy-sounding pianos. It's a major reason why I lived with a Shure V15 cartridge for many years. It's one of the reasons I was an early convert to Compact Disc. I got to say, though, that meticulous cartridge alignment and ongoing improvements in cartridge technology have largely made mistracking and end-of-side distortions a thing of the past.