Im not sure if it is intentional, but for every tier there are 2 maps and basically 1 map per tier is awesome and the other one is complete garbage. Biggest problem with most of the bad maps is that they either have terrible layouts, not enough mobs, or both.

Tier 1: Sewers vs Catacombs
Sewers only has 1 level but has tons of density. Both of catacombs' levels are a decent size but there are few mobs and they are spaced far apart. Also the boss just seems to spawn in africa sometimes.

Tier 2: Caves vs Crypt (which is actually called tower cellar)
Crypt is 2 levels of the Countess tower and caves is the best map in the game.

Tier 3: Durance vs Tomb
Durance is definitely a bigger room and has more mobs but tomb isn't too terrible. Its a good place to power level friends because durance is far too rippy.

Tier 4: Dungeon vs Maggot Lair
This is basically the T2 situation all over again. Dungeon is packed with mobs that are not too dangerous whereas maggot lair is very confined with charging undead that 1 shot you.

Tier 5: Temple vs Worldstone
Temple is superior simply for the fact that worldstone is just way too rippy, though Worldstone redeems itself a bit because it can drop divine gems.

Maybe just add a cube recipe where 2 of the same map creates the opposite one. For example 2 maggot lairs makes one dungeon.