The problem starts in "not her own" scenarios, where one careless move or bad morale can result in losing half a stack. Also, you can't take nymphs into Dragon Utopia-hives, nor into many ГО either.
Which of these outweighs the other requires tests in real games; it is difficult to evaluate this mentally.
In my tests for Jebs, Corkes showed the best results — he starts off mediocrely, but as he gathers 6-7lvl caches and canned meat (which is even more convenient for him to carry through swamps) and levels up, he quickly becomes a beast.
However, these were tests from a time when zephyrs and workshops didn't exist yet. With them, Cassiopeia's position definitely improves.