I have a sharp santoku knife that does better for plugs than other things I tried. The straight edge and thin blade help to make thin, precise cuts. I think it does a little better in that regard than a chef knife, as well as for mincing and fine dicing other vegetables, i.e. the kind you're supposed to eat for food.
The downside: It's a little bulky to carry around with you. I guess you could put it in a sheath or something, in case walking around with a pipe hanging out of your mouth isn't eccentric-looking enough.