I believe aliens have no reason to not genocide us immediately upon discovering us, so I'd rather be the only civilization. But to answer your question, absolu

I believe aliens have no reason to not genocide us immediately upon discovering us, so I'd rather be the only civilization. But to answer your question, absolutely the first. That way, if we are more benevolent than the Machiavellian necessity, we will either pioneer an improbable United Federation of Planets or be eradicated due to our idealism and naivete.