this thread is a little one sided, but screw it I'll play along , Luke Obviously wins, I mean all we have is atton who is a jedi killer so that's something, but carth is a weak link here, i mean he may have battled Karath on the leviathan, but we don't know how Carth contributed to the battle, just like we don't how atton was against Jedi during his time as a Sith assassin for Revan's Empire, his techniques for Jedi may work against Jedi who may something to lose but luke's alone maybe if Leia(RotJ) was with Luke, atton may be able to distract Luke for a brief period while Carth tries to gun luke down, even then nothing's guaranteed, maybe all they succeeded in doing was pissing Luke off even more.