The guardian shield gives you the most balanced approach for both basic blocking and parries, while perfectly-timed deflections auto-reflect projectiles back. When you're starting out thats your best choice since it handles most situations well

Each shield excels at specific combat styles though. The stone wall absorbs multiple hits and lets you store that energy, making it perfect against aggressive enemies that spam attacks. Dauntless is high-risk but devastating when you nail those perfect parries, the red glow means you can follow up with massive damage. Shatter star builds charge while holding block position and releases powerful knockback punches, great for creating space when surrounded

For pure mobility the onslaught lets you rush through groups while parrying, and once you unlock ng+ the spartan aspis rewards precise timing with enhanced counters. Really comes down to matching the shield with how aggressive or defensive you want to play, since effectiveness is about mastering each ones unique rhythm rather than any durability stats

Tip: practice shield mechanics on weaker enemies first since timing windows vary significantly between options