Who makes the best hand priming tool?

[Tesoro]

+1 to Mikecr's choice.

........K&M is sweet set up.

I am a tool junkie. Had that and then switched to 21C. John makes an adjustable primer pocket uniformer so can make all primer pockets exactly same depth. ( plus a great tool for cleaning pockets). And then he has a much more ergonomic hand seater that is adjustable with .00125 clicks. So you can pretty much adjust your primer to have the same degree of crush when the primer handle bottoms out...or can adjust up and seat by feel easily as the 21c tool handle has better leverage.

I also found the 21c tool to have a nicer shell holder. The k&m uses/used lee and not that friendly for fired cases out of an AR.

John used to work/make for sinclair and has improved on some of their great tools.

 

[Mikecr]

You must not have had or learned to use the indicated K&M then.
What the indicated K&M does beyond any (including the 21C) is account for primer heights -as well as pocket depth, and rim thickness. Each and every one. This sets primers to same crush, and there is no other way to do it in one tool. That's the genius behind it.