Are you going for XP, gold or equipment?
The Maze will likely give you more XP (I'm including both levels of the Maze). Depending on how durable you're build is, you might sneak out a little more gold from the Maze as well. That will be in the form of weapon drops from minotaurs.
If you're not able to last very long in the Maze, than the Mausoleum will likely be better, esp if you're a Cleric with a focus on killing undead. Skeletons drop a lot of shields, and there's a few places to find large Emeralds. But most importantly, if you haven't gotten a pair of
Ruined Dragoon Boots , farming the Mausoleum will give you a chance to find a pair. Those boots are useful in numerous parts of the game, including the final area of the Ark and final area of the Sewars of Horrors.