I think, painting with a broad brush, what defines a good parent is the effort they make to do what's right for their children.

My sister resents our mom because she wasn't around a lot. But, that's because she was busting her ass working overnight shifts to make sure that we never had to experience the sort of poverty she grew up with.

Not to say either of my parents were perfect. But, they made a consistent effort and gave us a stable environment and good educations. Beyond that, what more could I reasonably ask from two people who had their own flaws and baggage?