Blooddrinker is used in 75% of Mythic Sisters of the Moon logs. Sisters of the Moon, Mythic, 95th percentile, all tanks, rated on damage:
https://www.warcraftlogs.com/statist...050&dataset=95
BDK Talents, same data:
https://www.warcraftlogs.com/statist...ntinfo=Talents
Heartbreaker is a noob trap talent almost as much as Bloodworms are. Blooddrinker beats Heartbreaker even in constant 5-target cleave (which is impossible anyway since you can't have 100% uptime on DnD) in all metrics, as Tojara said.
Let's look at the #1 Mythic Mistress Sassz'ine logs:
https://www.warcraftlogs.com/reports...9&type=summary
In this fight, for perspective, Lynathel got rank 1 DPS and rank 2 Healing as a BDK, so the logs aren't skewed in favor of either DPS or Healing.
If Lynathel had used Heartbreaker, he would have gained 286 additional RP from Heartbreaker, which equates to 8 extra Death Strikes, assuming he had Gravewarden and Ossuary up for every one. Eight additional Death Strikes would have been 8.18m additional damage, using his averages, whereas Blooddrinker did 25.90m damage. Now for healing, those 8 additional Death Strikes would have healed him for an additional 16.12m, whereas Blooddrinker healed him for 16.84m. So nearly equal healing from Blooddrinker and Heartbreaker, but over 3x the damage, and that's ignoring the fact that he only cast 11 Blooddrinkers in the fight out of a maximum of 16. If he had cast all 16, he would have dealt 37.67m damage and healed for 24.49m, which is 4.5x damage and 1.5x healing, respectively.
There are the data. Heartbreaker isn't
terrible if the player is not comfortable with Blooddrinker, by all means, but Blooddrinker is definitely the best talent to take.