Zallow being considered a more noteworthy kill than Darach is a good accolade and Malgus's impression of him in Deceived conveys that he's worthy of distinction, but I think Kit's acknowledgement by three renowned masters in the RotS novel (Mace, Shaak, Obi-Wan) as one of the best swordsman in the order and the nod Obi Wan gives him in the Cestus Deception better substantiate Kit's place as a top dog of his era.
Feats-wise, I can't speak too confidently. I find Zallow briefly contesting with an enraged Malgus to be pretty good. His blitzing of no-name sith warriors (I don't remember any distinction being given to them in the narration) is not bad, but I personally find it comparable to Kit dismantling magnaguards and JK droids, which have their own descriptions attesting to their speed and adaptability in combat. Being acknowledged as a better swordsman than AotC Kenobi while gimping himself in certain areas like speed is nice too.
To put it succinctly,
Originally posted by The Ellimist
Kit Fisto is better in pretty much every category (feats, accolades, etc.).