It does depend on what work you are doing. Model engineering rarely needs the as-supplied hardened serrated jaws. I have never got around to making new jaws for my big and use pieces of softwood with a thin saw cut vertically on the working face. They are held on by rubber bands that hide in the cut for protection. They are 100% disposable so I can saw and file into them with impunity. They grip well by distorting around the work, or can be drilled to hold round work.
My small vice does have aluminium jaws that again can be sawed into. My medium vice is portable for use outside on car work but when needed I have two pieces of hardboard sheet with a bite taken out of the bottom that slips over the central bar of the vice to stay in position.
I'd like to make a set I have seen on the web that have a pattern of dowel holes in the top face. Adjustable height dowels can be inserted to grip plate and odd shapes. See the post by Rob
Aren't his photos good and I think he is British.
Edited By Bazyle on 17/12/2016 13:54:19