> There's no experience of any kind related to not existing in the first place, so the two options are completely orthogonal. It's like asking whether you'd suffer from your parents never having met.

I agree with your first statement that not existing in the first place means that you don't have the capacity (or burden) to regret or cherish that existence.

The second statement is a little bit more nuanced, because assuming you derive happiness from your existence, and you already exist, you'd not have been able to experience the happiness if your parents didn't meet, therefore you'd suffer a net loss. I realie that there's a bit of circular logic in there of course, hence why I condition the assertion on the fact that you already do exist and therefore can make a judgement whether you'd prefer to exist or not.

Hardly orthogonal: better to exist in suffering or not exist is rather acutely the topic of interest to those contemplating suicide.

Again, two different things - ending an existence, versus there being no existence to begin with.

Conflating the two makes one argue ethics from a realm of infinite possibilities instead of focusing on reality, which doesn't really make for great moral choices. For instance, should people have as much unprotected sex as possible, without any regard to their or their offspring's well-being, just to give the most children the chance to exist?