Parry...

[Zourin]

I would think accuracy is an overrated stat, as you'd have to be missing pretty badly and routinely to lose threat, and there's typically plenty of accuracy on gear to keep a tank afloat. It's more a DPS stat than a tank stat, although I would definitely take accuracy over Det.

There's very little information I can pull up to separate practical effect of accuracy (which only affects dps, and by proxy, threat hold) for tanks from min/maxer theorycrafting (which grossly overrates immeasurably small, borderline subjective gains). Best in Slot is largely an empirical factor for the role: Tanks absorb and deflect damage, so it's about Parry as the only defense-oriented secondary stat. If you are not having issues holding threat, you don't need more Accuracy or Determination.