Merchant

Innkeep Morpa

Morpa's bread shipment quest grants the most overall experience of the bread shipment quests. Kaladim's gives an equal (maybe even slightly greater) amount of experience per individual turn-in, but is only available for half the day because the NPC despawns at night. Morpa's muffin quest gives a hair under 4% experience at level 9 and between 2-3% at level 10, as a druid. That means it likely (untested) maxxes out the exp reward until level 6 or so.