There are quite a few, the most powerful by far being the one you get from killing Crusher (the goblin at the camp you make kiss your foot).
I'd argue the Whispering Promise is more powerful; it means you can have no-concentration Bless on a single character every round for the cost of eating an apple; especially on a Thief where the extra bonus action can be used. But opinions differ I guess.
I use Shadowheart in my party for Bless, and she's the highest AC member of the group, so concentration is rarely an issue, and when it is I just cast Mirror Image.
Shadowheart with my druid PC gives me two people to heal and rez from range with, and Inflict Wounds rank 2 with exposing bite from wolf form is the nastiest combo in the game if you don't cheese rogue stealth surprise attacks with Wyvern poison.
