For what it's worth, I think you should go with the Galaxy. I have and use both the iPhone 5 and the S3 on a daily basis. Love both. But for me there's no doubt that the iPhone is my clear pick of the two. So I'm able to put up with these quirks and frustrations that Apple ocassionally puts out. Also a former employee so it's possibly still in my blood.
Don't get me wrong, I'm ****** at production quality issues, but can also understand it's a trade off of elegant design. There's a reason a tank doesn't look like a Ferrari, or that an Otterbox case looks like it does. So we love the light and jewelry design of the glass an aluminum, that's what the trade off is.
But with Apple products, if you love the platform, you can complain, but always end up putting up with it in the end. That's why all of us are here, to gripe about how disatisfied we are and how we hope something will be done. Because, any of us should be able to go and return it and get a refund, but we don't. Why? Because we know there is no alternative. It's illogical and doesn't make sense to most people.
This is why I say that if the S3 is really does suit your needs just fine, I'd say go for it and not worry about all this mess. Realistically, there is little Apple will/can do about this. And "Apple Arrogance" will ensure that they won't have to.
The S3 is a beautiful phone and I must say I love the gadgets and customization you can do on Android. Some people say the S3 is cheap, but I think it's fine. Yes it's plastic, but ironically the plastic is holding up well to nicks. Drop tests aren't as good from what I've read so far.
Last thought is that if you decide to stick with the iPhone, the good news about yours coming late, is that there might be chance that it comes better built. Good luck in either way you go.