We have had great luck with apple cider vinegar (been doing it 3 or 4 years now with great success), the rest is all new to us.
Yesterday we checked on the potato wine vinegar and the top was covered with mold. I am not really sure why, but I got thinking that "bad" wine is probably not a good thing to try to make vinegar with. "Good" wine would most likely work a lot better.
Maybe the potato wine didn't work out because the taste was never quite right for vinegar, so I just let it sit longer and longer (it has been almost a year, usually a vinegar will be ready in 6 months or so) and it finally just spoiled.

