From what I've found, your best bet is going after jade the vampire hunter, who patrols around dunley farmlands. She's level 57 and once you take her down, you'll unlock the advanced blood press which is really what you need here. The press lets you work with two different recipes, and honestly the greater blood essence route tends to be more reliable even though it needs 8 pieces instead of 4 exquisite hearts

The most efficient approach is to focus on farming regular blood essence from enemies, since you can convert 200 of those into one greater blood essence. Sure, you could try hunting down exquisite hearts from tough enemies like werewolves and night lurkers, or even the paladins hanging around silverlight hills, but that's usually more trouble than it's worth

Something interesting to note - if you're planning to make a bunch of primal blood essence, setting up a good farming route for regular blood essence is going to serve you better in the long run. The conversion process might take longer, but it's way more consistent than hoping for those exquisite heart drops from high-level enemies. Most experienced players stick to this method since it's just more dependable when you need a steady supply