I cheat 😁 I don't care what the existing angle is, I use 30 deg for bench chisels and 20 deg for paring chisels and I sharpen on my Worksharp so I just set the jig and let it do the work.
I will add that in addition to the bevels, I give attention to the backs when I first acquire a chisel and flatten them. For wider chisels I also flatten the backs on my Worksharp. For narrower ones that are hard to hold flat against the spinning wheel, I use diamond plates. Unless they really need a lot of work then I put some 60 grit sandpaper on a granite surface plate.
Nathan, for bench chisels I've become fond of the Stanley 750 style handles. They're comfortable to hold while hitting the butt. If I were making my own I think I'd keep the basic geometry but make them a bit longer so my fat paws aren't so close the the mallet. For paring chisels I like EA Berg handles. They're big enough to hold comfortably while applying force and strong enough to take a mallet tap if needed. The rings indicate they're intended for mallet duty but I like them for hand use.
