An Attempt to "bring it around"

OK, I will pre-empt an answer to my simple question from the Onto apologists:

-My point was this: I think that with whatever answer any one could possibly provide (and again, I'm assuming now -- that's why I wanted an answer) to the question: "Why is it greater to exist than to not exist?" Would reveal some underlying assumptions about the term "greatest" in the first place, and then second, it would show that our attempts to quantify anything as greater or lesser comes from experience (even it is experience of "existance"). So often people would just say "well it just IS better to exist than not exist" to this question. But if you get down to WHY is it better -- it will reveal the way your mind is thinking and drawing from experience (yes?).

The point of that? I still think the Onto is dependent upon a posteriori knowledge. Therefore, it really doesn't do much for us -- it is superfluous.