Although Malgus had more showings, Marr seems to be written as being just as powerful (being second to none within the empire, slayer of armies and a threat to the Emperor with Darth Mortis among his accolades). I think Marr could replicate the things Malgus has done imo.
SunRazer
Malgus wins.
carthage
Malgus is the greater duelist and force wielder, he wins
