If you can choose, one parent doesnt need to work... Stay at home mum or stay at home dad?

I'd say this largely depends on your family! Other than just looking at the income earned by each parent, you should also look at other things like which parent the child is more comfortable with, working hours of each parent, responsibilities at work etc. In any case, please discuss it with your spouse because it has to be mutually agreed upon to avoid future conflicts - the one working has to financially support the family, while the one at home has to look after the child's needs and household chores - both being fully understanding of how hard the other person is working!