"An aspiring corsair seeking to become The Left Hand of Prophecy is advised to become obstinate, at least until their stats are high enough to reliably 100% checks, at which point a Nyx is probably preferable."

As a Corsair who can reliably 100% all checks aside from highway stat checks in the Snares, I can safely say you want to stick with Obstinate regardless, especially if you're grinding Zhip-hunts or Zee-hunts. There's nothing wrong with picking a Zub for fun or roleplaying, but as a Corsair, you WILL be taking on a lot of Troubled Waters even on successes. And thanks to the fact you will very rarely get Zee-menaces from your constant successes, it can lead to dangerous situations of being at 7 TW and having no cards that can lower your TW.