The Winner: T3 Alicorn Headguard
Between the two options, the T3 Alicorn Headguard is the superior choice for your next upgrade.
While Sanguine Greaves are an incredible item for their raw stats, the Tier 3 effect on a Helmet (Momentum) provides a mechanical gameplay advantage that legs simply cannot match.
Here is the detailed breakdown of why the Headguard wins for your specific situation:
1. The Power of "Momentum" for RPs
Tiering a helmet grants the Momentum effect, which gives you a chance to gain a proc that reduces your cooldowns by 2 seconds.
For Paladins: Your rotation relies heavily on Divine Caldera (exevo mas san).
The Synergy: Mas San has a 4-second cooldown. When Momentum triggers, it effectively allows you to cast Mas San much more frequently (skipping the cooldown wait).
Result: This directly translates to higher DPS and, crucially, higher Life Leech.
2. Synergy with Your Hunting Spots
Your specific hunting grounds heavily favor Holy damage and Area of Effect (AoE) rotation, which benefits massively from the Headguard's Momentum effect.
3. Equipment Slot Value
Helmets (Tiered): Active gameplay change. The Momentum effect changes how you play and raises your damage ceiling.
Legs (Sanguine Greaves): While Sanguine Greaves are Best-in-Slot (BiS) for stats (protection/distance), upgrading them to "Tier 3" typically offers Convergence or Reflection, which are defensive/utility mechanics.
The Trade-off: In the current meta, Offense is the best Defense. Killing the "box" faster (Headguard) prevents more damage than the Greaves would mitigate.
You already have the T3 Sanguine Bow (Onslaught), which handles your critical hits. The next logical step to maximize your character's power curve is Momentum (Alicorn Headguard).