Playing on Atiesh, level 87 rogue Runrenfri, MoP Classic.
Darkmoon Faire dungeon drop quests don’t give the same XP, when it seems like they should. In fact, the level 15 minimum ones give more than the level 85 minimum ones (not that that should matter since they scale UP to your level).
The Soothsayer’s runes and Treatise on Strategy quests award 76K XP
The Monstrous Egg and the Imubed crystal give 142K XP.
Wasn’t able to test the Mysterious Grimoire yet, but as it’s level 15, I imagine it gives 142K XP.
edit: Profession quests gave the same 141,900 XP, skinning/LW/cooking/First aid. They originally said ~129K but actually awarded ~142K. I’m sure the extra 10% is from a guild perk.