I think that 'selflessness' on the part of a parent can be damaging to children, as it can encourage them to grow up not realising that others have needs too. Also, people who do things in the expectation of thanks or appreciation are setting themselves up for disappointment, whether as parents, friends or spouses, as people don't like to feel beholden and can be resentful.
Quietly putting children first is, I think, more likely to result in a good relationship when they grow up. The details will vary, but I'm thinking of things like doing without a holiday yourself so they can go on the school trip, or not buying a new 'thing' (insert other item of choice) but paying for driving lessons. Done properly, the child will never know about the sacrifice, but will appreciate the result.