Opinon of villains for campaign?

[Berselius]

I'd like some opinions of the main villains (shown below) of my campaign (my PC's will be starting at 10th level):

Chamber of Horrors:

Maelvos; CR 12
LE male half-elf cleric of zon–kuthon 12

Temple of Skulls Shadow:

Leshlya; CR 14
CE female drow oracle (bones mystery) of urgathoa 14

Revenge of the Ice Queen:

Karla; CR 16
NE female human druid [arctic druid] of Baba Yaga 4/sorcerer [boreal bloodline] 4/mystic theurge 8

Rebirth of the Witch King:

Iygnehz; CR 18
CE male wraith antipaladin 13