If you store wine and it goes bad, it still has some value as vinegar. Wine that is well preserved will be widely prized for Communion purposes.
However, for a trade item, hard liquor is your best bet. You can pour it into smaller containers, water it down, mix drinks with it, and a bunch more stuff. I guess what I'm saying is that its more versatile than wine.
The biggest threat to ANY alcohol that you may have stored is if some booze hound or wino gets into it. Especially if they are good at hiding their alcoholism.
The good news is that none of the Militiamen that I've trained with have alcohol problems. Its just not an issue with any of them, which is great. However, who knows what kind of dirtbags might be showing up late to the party.