Once we already exist we want to continue existing, but before we existed we did not care if we existed or not. So what is better? Is it better to bring new life into existence? And the more we bring, the better? Would it be better if god had made the world lifeless?
My opinion is that existence is neither better nor worse than non-existence, rather they are incomparable. The reason why I think this is the following: I think that whether one state of affairs is better than another depends on how "well" people are, that is, people have certain desires that they need to satisfy, and the higher the ratio of (satisfied desires) / ( desires that you need to satisfy), the better that state of affairs will be. So the more desires satisfied, the better, but also the fewer desires they need to satisfy, the better, since they are more satisfied with fewer things. The problem is that if you don't exist, you have neither satisfied desires nor desires that you need to satisfy, so the ratio would be an indeterminacy of the type 0/0. That's why I think it can't be compared.
Edit: More specifically the question is, is there anything about existence in general that makes a state of affairs in which someone exists better than one in which they don't? (Although later for other reasons you can add or subtract value to the existence of a particular person).
By better I don't mean better for something, but better in a moral sense. That is, I understand "better" as "more good", assuming that good exists.