I love root beer! I believe out of all those brands, I'd have picked A & W too. Not that I've tasted all of the ones rated, mind you; I just think it's a great root beer.
We still have some A & W root beer stands in our area.
The best root beer of all time IMHO is Frostie root beer. And boy does it bring back some good memories.
I guess it isn't common enough anymore. We see it on a limited basis a couple times per year, and when I do I buy it up.