PLD theorycraft?

[Rbstr]

The main thing is a logical agrument: The real threats to tank survival in coil/endgame come from spike damage attacks. Most of the rest of tank damage is pretty trivial to heal and requires no mitigation. So while parry may reduce the total damage you take in an encounter it can't be what saves you from a spike attack or you're simply relying on luck to survive. Luck that happens at less than a 30% rate - so clears don't happen when you rely on it. It does not increase effective HP, it is purely an incidental bonus no one can count on.

I'm not against parry completely - adding strength is way more useful than changing a parry item to a det item (At the end of the day 150 parry is like 3% total average damage reduction. 150 det on a tank isn't going to up total party DPS by that much...but it will make for a large increase in your enmity!). If you wanted to meld Topaz with strength that'd arguably be better than ruby with vit, since Palys can get into TP trouble.
I suppose if you wanted dex for some reason you could do i90 accs with dex.vit.str. But a point of parry gives you more parry rate than dex does...and it does nothing to help DPS like determination would.