A Paladin's opinion on Parry

[PROBOUND]

Donjo - the shield is irrelevant since every build has it.

Shield Type does have some relevance. Tower shields favor parry more than Kite or Buckler shields. The more you block the less parry is significant yes. However, with Tower shields the Block Strength is much higher and Block Rate much lower. This makes it so that when you do block, they are Manly Blocks (Sentinel 2.0 40%), but if not your parry will make up for it. Parry Shines in these situations. You are not stacking parry to ensure you parry. Your stacking Parry to ensure that if you don't block you parry.

Donjo does a great job of laying it out in this post

The only reason it may not be relevant is due to the fact there are no i130/i135 Tower Shield Options in the game. If SE made it so that PLD's would have a choice between shield types of equal iLvl, this is where Parry sets/itemization would benefit. Here's hoping for more Shield options in HW.

IMO: All PLD's should have 2 sets and essentially 2 BiS. A set for Progression (Parry) and a set for Farm (Crit/DET).

TLDR:
(Tower Shield) Higher Block StR + Max Parry = Good. (Max parry will benefit from the shield)
(Buckler Shield) Low Block Rate + Max Parry = Bad (Better to go with Crit/Det)