I tend to like Maple Leafs, then Eagles, then old coins. The old coins are good because many of the things you'd want to buy will cost less than an ounce of silver, so just having tons of Eagles makes it hard to trade. Old coins give you an important ability to trade set amounts of silver in known purities and quantities.
I think that in a SHTF scenario, the old coins would do okay. Initially, sure, 99% of the people probably won't take your old quarter. But those are probably the same idiots who would still take cash. When it comes down to it, silver and gold have always been accepted as currency, and should paper currency fail, the coins are still worth their weight in silver and would come to be viewed as desirable once credit and paper money were no longer accepted. As Rob says, I see the coin, and I know it's 90% silver, or 40% silver, and then we can negotiate what we think it's worth in trade.
That's why I tend to stay away from numismatics. They're nice, precious and have a lot of history, but I'm describing a different coin collector. The coin collectors on this board are probably more concerned about sustained high-inflation or a hyperinflationary event where the FED notes become worth bunk.
I guess the good thing would be we could all pay-off our paper debt, be it mortgage, school or car/truck debt with just a portion of one paycheck! The only problem would be trying to come up with money for milk if it's selling for $100 a gallon.