Do labyrinth, if you score at least 600 (650 after boss), you will get around 70k exp. If you figure the wilds get you around 500-600 exp per stamina, even at the 2nd lab, costing 60 stamina, you would gain only 30-35k exp, while getting 70k in lab.

Oh and also, you can get extra gems/tokens in it from the random chest squares.