*slaps forehead* For god's sake people, stop arguing with Mars and Ace Pace. They're both right on every account.
Freespace ships move in meters per second. Star Wars ships move in equivalent to kilometers per second. It only seems the same because in the games the ships are pretty damn far off, though subspace has an edge over hyperspace. It take seven minutes to jump from Delta Serpentis to Sol, while it takes the Millenium Falcon, in all its .5 past light speed (LIGHT SPEED, man!) to get to Alderaan. Admittedly, light speed is fast, but it's seven minutes, man.
The Lucifer would easily defeat the Serenity and the Voyager, and in turn the Death Star would easily defeat the Lucifer because it has magical planet-exploding lasers. If we're talking about the Death Star II, it could easily take out all three ships with minimal damage, and if they get too close it could unleash the thousands of turbolaser batteries it houses, and that much firepower even without the laser would overwhelm even the strongest shields. Hell, it has an edge over a Sathanas, possibly a fleet of 'em.
Any Death Star would win, hands down.