What matters most is the abolition of institutional slavery for the first time in human history by the House of Commons in 1833. Followed by the emancipation of women for the first time in human history in Australia and New Zealand in 1904. Followed by the criminal prosecution of child, sexual abuse for the first time in 1996.
All these recent social gains are the fruits of liberal democracy arising from the Enlightenment.
The Enlightenment also gave us universal literacy, the, "Origin of Species" and the sequencing of the genome, not to mention General Relativity, the Periodic Table and Quantum Mechanics.
The Enlightenment also gave us modern Medicine based on evidence and reason.
And the Enlightenment also gave us, via Adam Smith, modern economics which has overcome scarcity for the first time in human history.
But perhaps what matters most is that our child rearing practices have improved from the sacrificial form, to the abusive form, to the authoritarian form to the helping form of child rearing where we help our children attain their goals.
And it is the helping form of child rearing that is producing more and more empathic and creative personalities, unhindered by the nightmare of past child rearing practices.
And it is the Enlightenment that woke us from the nightmare.
I'm inclined to say respect. Respect towards yourself, others, everything around you. When you think about relationships (any kind), this is where everything starts. Without respect there can't be any positive progress. Well, there can be but it tends to be one-sided, neglecting other variables in the equation, and in the long run it's not positive at all even though it might seem so at that particular moment.