Fatty, when a previous poster said children with working parents do better at school, they don't mean in every single individual case of course, but on average. It is quite possible for your children to do brilliantly while you don't work and for the children next door to do poorly whilst their parents both work, and for this statement to be true. It is one of those statements which is extremely difficult to test and prove either way.
I agree that unconditional love, security and boundaries are the most important.
If I could add a next level of importance, assuming the most important have already been met, I think that learning social skills, in order to function in the wider world is very useful as children grow up - these include a sense of respect for others, a sense of own self-worth and an ability to get along with a range of people.
In material terms, I agree that what you have isn't so important, but that having parents who are so much on the breadline that they constantly worry about money, cannot instill a feeling of security in children, although I know parents in this position often try to hide it from children and to protect them from it.
And I think the relationships the key adults around children are in, are important in shaping children too. Separation and divorce, whilst sometimes necessary, nevertheless have consequences for children. In an ideal world, I do think children would have 2 parents who are happy to be together.....experiencing separation or divorce is very hard for children. I know we are not in an ideal world though.
Being with a parent who has many partners who come and go over time seems very damaging in lots of ways to me. Children need security and consistency and if there are frequent new boyfriends and girlfriends, it can be difficult for the children to know where they fit it and if they are the priority. When children are involved it concerns me when parents introduce a new boyfriend/girlfriend quickly or move in together quickly. Some children go through this multiple times, and I can't see that this can help with them feeling secure.
Feeling like a valued part of a family is important - building shared memories together, knowing that you are important and would be much missed if you weren't around, gives you a sense of belonging.