This argument goes on and on. I recently bought a couple Better Bottles(3 gals), they are NOT the collapsible type but are square and rigid. Personally, in my opinion only, they are easier to handle(weight wise) and apparently are safe for use with alcohol, even for long term bulk aging. I will post the website for them in a second. Decide for yourself. This is a subject I brought up in the begining days of my wine making "obsession" and I refuse to keep it going. We may as well argue whether or not you like Toyotas, Chevy's, or Fords.
Use the search engine in here and see the 500,000 threads and posts about this. I would prefer to use glass, and the better bottles are about the same cost. The bung is the same diameter as glass and anything that can be used on glass will work for a "Better Bottle"
Troy