Corran should likely take his ancestor. Nejaa sounded pretty impressive, but Horn's one of the top Jedi of his day, and fought plenty of impressive foes.
It's an interesting duel, in that no TK will be used, no lightning, both can potentially absorb lightsaber energy, both are good duelists (although I personally think Corran is better- Tyris did manae to kill Nejaa with an unexpected move), and both have good illusion skills.
Corran does have the advantage of more screen time/feats, so he's actually shown more illusion and dueling feats. And he has a few tricks, like his extending saber, which help as well.