Depending on what kinds of qualities you want your lines to have I recommend the following:
Engraving Burin - a slightly awkward tool but capable of beautifully clean line variation. See Durer or Schongauer for examples. Echoppe - useful for line etching and can mimic a lot of engraver's marks. (I made my own by belt sanding a thick needle at an angle and putting it into a pin vice.) Sugar lift/aquatint - not very clean, but you can get some great lines that will do most of what your brush will do. Not great for very thin or delicate linework. See my pixie prints: one, two, three. Drypoint - easy to use and intuitive with pressure sensitivity. Difficult to wipe sometimes. See Rembrandt's drypoint etchings.
I did a lot of lithography in school, but I don't have the equipment for it right now. Lithography is pretty great stuff and I could probably get back into it, given time and supplies, but I do love etching copper.