Would love to see Plagueis vs. Darth Caedus.
While Legacy writers were horribly inconsistent with the writing, Caedus's feat of holding his own with his uncle should be on par with the best lightsaber moments in the mythos. Plagueis's dueling skill isn't explored well, but his physical strength, battlemind, and speed would be a great counterpoint to Caedus's skill.