Just to make this clear, the name Benatar refers to the person who made the argument first, David Benatar, in his seminal antinatalist book Better Never to Have Been. While he presents other arguments from other thinkers, it is more or less the central argument of his book.

Benatar's Asymmetry Argument: Response:

While it is true that life undeniably brings some level of pain, is it not equally bad to deprive a potential life of all the pleasures that surely come from living? In most cases the joys of life far outweigh the negatives. Of course, it also depends on what forms of harm we’re talking about, but most people experience minor levels of pain (being teased) as opposed to something more harmful (getting a leg blown off in war), and oftentimes these minor levels of pain help in building a person’s character and helps to shape their morality (they know what it is like to be teased and befriend others who have gone through, or are going through, the same thing). So I would also add that pain, in and of itself, is not always a bad thing. Good things can actually come from it. I think this argument is painting the situation as black and white when there are actually many shades of grey. Put simply, the various levels of pain experienced in life are not always bad and can sometimes be beneficial.

Ken, did you not read the sentence:
"On the other hand, no potential person can be deprived of any pleasure, so any pleasure experienced by the existing person is irrelevant, and these two terms cancel out."

If so, what part of it do you object to?

"So I would also add that pain, in and of itself, is not always a bad thing. Good things can actually come from it."

Actually, I agree, and that's a pretty important point. Positives can only exist because of the negatives. Without desires and their accompanying harm, there would be no positives. So while it's important to acknowledge the existence of the positives, it's also important not to confuse the disease (desires and harm) with the cure and its effects (pleasure). The cure is only needed because of the disease.

However, you are acknowledging that the harm exists. Whether it leads to some positives to exist is not relevant, because no potential person is deprived of pleasure. So this argument hinges on the first one. If potential people suffered because they were deprived of pleasure, then it might be good to start their lives in order to palliate this suffering (although we would still have a duty not to create the harm they will incur). But this is not the situation we're in.