You want easy? Stay on Parum.
You want hard? Go to Moatoob.
Moatoob is a jumbled assortment of all the worst things from Parum and Neudaiz. It's got palette-swapped Kagajibari's as normal enemies and not sub bosses; it's got Shagreece that paralyze you; it's got flamming-feces throwing Vandas(I don't like monkeys now ;-

; it's got Dimmagolus; it's got annoying Leaders who know just when to command their minions to rush you; and it also has Neudaiz' bullet time if you're on PS2.
Moatoob is evil. D: