which is better, Parry or Shield Block?

I need to know your opinions. MRD parrying or PLD shield blocks? and if you can explain why as well (I know MRD has high health/vit etc and it's the best tank. I need to know about the parry and blocks)

Both are equally important. WAR and PLD each have skills that are reliant on blocking/parrying.

I think he's looking to find which one negates more damage, how frequently they proc without buffs, what buffs are avaliable to them and what you gain access to from having a proc.

I'd answer but in all honesty I don't really keep track of how much I parry or block, I'm too busy looking at other things

a PLD blocks more than it parries, as far as damage negation goes blocking is based of your shield + stat modifiers while parry only blocks a set amount of incoming damage i'm unsure how parry negation is calculated, all i know is both shield & parry proc rates are modified by the DEX attribute.

its a trade off for pld.
to block more damage but proc less add more STR
to proc more but block less damage add more DEX