hey Barønshekel Condensed Life-Force (Guardian of Azeroth + Condensed Life-Force) adds a very powerful 3-minute cooldown which lines up nicely with Recklessness. The summoned Guardian of Azeroth contributes a good deal of damage, typically around 5% of your total output over the course of an encounter, and also continually triggers the minor effect Azerite Spike, which increases the target’s damage taken. The essence is also very competitive for sustained multitarget, although packs rarely last the full duration and the long cooldown is prohibitive.
Blood of the Enemy (Blood of the Enemy + Blood-Soaked) is a very competitive essence which shines in multitarget situations or when the lower cooldown aligns with encounter mechanics. It syncs very well with Recklessness, and especially Reckless Abandon, seeing a lot of use in high Mythic+ dungeons for concentrated burst.
Essence of the Focusing Iris (Focused Azerite Beam + Focused Energy) is the best constant AoE Essence, often competiting with Blood of the Enemy. Because the cooldown stands alone rather than enhancing player damage, it allows more frequent burst periods, which lends itself to lower Mythic+ dungeons with fast pulls. Depsite having slightly lower burst potential, it has the highest raw AoE damage potential of any essence. Conversely, the minor power is single target focused, which lends this Essence to being used to burn down adds while focusing a single major target.
All 3 are good and have their place on the Fury toolkit.
don’t feel forced to get a specific one
remember, the most important is to have fun!!