There are many different styles of bolt knobs, I prefer Badger Ord for the work horse no fuss knob. I also like the selection of different sizes of knobs Kampfeld Custom does. My 450 Ultra Mag is currently at Kampfeld having some custom work done that includes his smaller ( Hunter ) bolt knob. I like the mid size knob for a hunting rifle, just enough to get a sure grip with gloves on but not oversized like the Badger. There are allot of gunsmiths that do them.
I'm going to have High Country, one of our own members here do some for me when he gets everything finalized. He posted a picture not to long ago of one of his set ups for doing bolt handle work.