Whom to give Guardian's Heart: Undying King or Elf Queen | All Outcomes & Rewards | Remnant

Once you have the Guardian Heart, you have 2 options:
Option 1: Give to Undying King
Option 2: Give to Elf Queen

Option 1:
1) This is easier Option. Get Labyrinth Key Without fight
2) Reward: Riven(Melee Weapon)

Option 2:
1) This is difficult Option (Undying King Boss fight)
2) Rewards: Crossbow, Slayer Armor Set, Undying Heart, Kingslayer Trait

-----------------------------------------
Played on PC:
Intel i5-7600 CPU @ 3.5Ghz
GeForce GTX 1070
-----------------------------------------

Remnant from the ashes Game Guide :

-------------------------------------------

Remnant from the ashes walkthrough,
Remnant from the ashes gameplay,
Remnant from the ashes game guide,
Remnant from the ashes wiki,

remnant from the ashes Giving beast's heart to undying king,
remnant from the ashes Give beast's heart to undying king,
remnant from the ashes Giving beast's heart to elf queen,
remnant from the ashes Give beast's heart to elf queen,

remnant from the ashes whom to give Guardian's heart,
remnant from the ashes who to give Guardian's heart,

remnant from the ashes whom to give beast's heart,
remnant from the ashes who to give beast's heart,
remnant from the ashes beast of the swamp,

remnant from the ashes guardian's heart,remnant from the ashes Giving Guardian's heart to undying king,remnant from the ashes Give Guardian's heart to undying king,remnant from the ashes Giving Guardian's heart to elf queen,remnant from the ashes Give Guardian's heart to elf queen,remnant from the ashes Guardian's heart all choices,remnant from the ashes Guardian's heart all endings,remnant from the ashes Guardian's heart all rewards,