I get depressed .....

The reason that I'm only considering the harms is because that scenario imposes a harmful burden on some, for a benefit that wasn't needed and wouldn't have been missed in a barren universe. 'First, do no harm'. If you can give everyone a blast with a guarantee that there will be no harm, then that would be a different situation. But as it is, to reproduce is an attempt to fix something that isn't broken, and have the cost of that borne by unlucky people who couldn't consent.

I've never claimed that a non-existent person could be imposed upon. Impositions can only be visited upon the living, and the biggest and mother of all impositions is to force someone to live who could not possibly refuse. You can't compare how one living person would feel about being alive to how one person would feel about being non-existent, because nobody could ever be non-existent to be able to have any opinion on it.

Before you were born, you were not in the slightest bit desirous of life, or feeling that you were missing out on anything, or eagerly anticipating whether you were going to be incarnated into a body to be able to experience existence.  That's the context. If we start from the basis that everyone's wellbeing is equally important and valuable as everyone else's (which is not an unreasonable starting point), then the optimal state of the universe from a wellbeing perspective is for there to be no sentient beings under threat from harm, need or deprivation. Such a condition obtains in a barren universe. To create life in anything but an environment that is permanently free from harm or suffering is a step from a flawless state to a problematic one, unless you're arbitrarily deciding that only the people who got the long straws are worth caring about and that blind luck determines who is worthy of the benefit and whose misfortune is a price worth paying (which is basically the platform of the Republican Party in the US encapsulated in a nutshell). The only way not to bring new harmables into existence is not to allow procreation at all.

That's not my point at all. The point is that there can be nothing wrong with not existing, whereas there can always be something wrong with existing. Since it cannot be known how much a child will suffer, or how well it will cope with suffering, then the non-aggression principle dictates that the child must not be born. Never am I taking into account the wellbeing of a non-existent person, only a person who will exist and whether there were justifiable grounds for the risk to be taken.

And when you claim that it's 'better' to have the option of living or dying than not to exist and have no option, you are making a comparison. Saying that something is 'better' is always comparing it to something inferior (and in this case the thing that's allegedly inferior doesn't exist, so there can be no valid comparison drawn). That's just the definition of the word:

Nothing is needed and there's nothing to be fixed. When parents decide to have a child, they can't be making that decision in the interests of the child, because if they didn't have the child, there would be no child that they were letting down. If there are no conscious entities, including observers in a universe, then there can be no flaws. There can't be anyone in need of rescuing. I meant optimal in the sense of lack of problems to be perceived in need of fixing. In a barren universe there aren't any problems going unsolved.

As for the GOP, that was a mild comparison. Your attitude is actually more akin to the justification of slavery. Why worry about all the black people who are being forced to work against their will and without pay? Why not focus on all the white people who are having a great time, aided by economic benefits of slavery? In both cases, the subjugated class is separated from the oppressing class only by something that was determined by lottery of birth, and yet is used as a justification for accepting the divergence in outcomes.

If there's nothing wrong, then nothing needs to be made right. And you can only have 'right' if there is possibility of 'wrong'. And if you say that it's not important to consider the welfare of those who don't yet exist, then you're condoning all manner of recklessness with regards to the environment, sociopolitical issues, etc. Someone who will exist is going to have to be burdened by an imposed existence which was chosen for them without their consent.

When you are dead and no longer exist, you will not have any preference for having existed over having never been born. Whether most people do go on to prefer existing does not justify allowing those to come into existence who feel burdened by their existence. If the welfare of black people is equally important to that of white people, then we can't wave away slavery as though it wasn't important because it was only happening to a minority (and a minority which was characterised by lottery of birth, at that) and the majority in that society were not slaves and even benefited from slavery. It's no different here. Some people are born to be collateral damage, whilst others are born to reap all the benefits. And it's a lottery which determines who will fall into which group. You can only say 'the suffering of the minority doesn't matter, because most people are happy' from the secure perspective of someone who was born with a good measure of luck and looks set to retain that luck. Whereas if you didn't know coming into it what luck you were going to have, but were able to make a decision about whether or not to be born, you might determine that the risks weren't worth it.

Right, before sentient life there was nothing to be broken in the universe. Since sentient life has existed, there has always been some kind of grievous harm to be avoided, and a threat of suffering that motivates living creaturs to pass on their genetic material.

There's no benefit to anyone other than the parents in taking the deliberate action to bring a new life into existence. When the new life becomes extant, it becomes burdened with the millstone that the parents decided needed to be hung around the neck of someone who couldn't refuse consent, in order that the parents can get what they want out of life.

So far, there are no credible proposals on how to make human life work without the need to have the metaphorical (and sometimes literal) slaves toiling away and being brutalised on the plantation. So as far as can be projected into the future, the 'better time' is still always going to come at the expense of some people and some animals. The only point that you're making is that it appears to you that the slaves are in the minority, and therefore their suffering is a price worth paying for your happiness.

To have children is to create slaves to your desires. As much of a 'blast' as you're having now, you wouldn't have missed a single minute of it had you not been born, nor will you miss any of it once you have died.

It seems to me (and sorry but I am not reading through pages of this to find out if you have given thought to it) that you are precluding the possiblity of there being a life other than this.  Is that the case?

EDIT:

Apologies for the formatting had issues getting this to display the quote.

you mean like this thread? seriously guys this is 26 pages of you two going at it hammer and tongs!