I have 2 girls, I feel that it is better as they can play together very happily, though sometimes they will quarrel. Having brothers or sisters can help the kids to learn more about caring others and sharing with others.
For us, one parent can take care of one kid, so seems that everyone is happier. Of course we have to spend more, but afterall we earn money to spend in a way we feel meaningful and happy, so I don't border too much if we use up our earnings. Govt is using our tax money to pay for the livings of so many families who only stay at home without working, so why we need to worry so much?!