OK, NASA (or some agency) has chosen you to be the commander of the first expedition to Mars. As commander, you get to be the first to step out the door onto Martian ground. And of course the whole world is going to be watching and listening to what you say.
So what do you say? What immortal words do you utter as you plant your toes in the red dust of Mars? Can you do better than that Neil guy?
“Google is your friend. Have you checked Snopes yet? Hurf durf I think Cecil did an article on this already. Habble gabble pulling up a chair and opening a beer!”
“As we sped along these last few months in the Coca-Cola ™ Mars Lander, my constant memory was that nothing is more out of this world than the cool, refreshing taste of Coke ™ popglug.”
On a more serious note, I would eschew making any notable quote. Just go about doing The Science. Say the same things the 10th person landing on Mars would say. Provide data. Armstrong showed what not to do. You can always make a thought provoking statement some other time.
I think Bradbury said, after the first Viking probe landed; “Well, we are the Martians now.” I’ve always liked the sound of that one.
…Say, what were the first words of the Nazi astronaut mentioned in The Man in the High Castle? Something about “Plenty of air, but nothing to breathe”?