One "nice" thing about NF is that it has only two axioms/axiom schemes: 1) sets with the same members are the same, and 2) any stratifiable property corresponds to a set off all the things which have that property. And the definition of "stratifiable" isn't very complicated.
ZF, by contrast, has eight rather ad hoc axioms/axiom schemes.
ZF, by contrast, has eight rather ad hoc axioms/axiom schemes.