This is more than likely going to be one of those "debatable" subjects, especially to the can specialists! I for one like the bigger cans and feel, from what I've seen, that they are more scarce than quarts. The "argument" I've heard is that there are more one quart collectors than 5 quart collectors, so even though they may be more scarce, they do not have the desirability of the quarts. I for one think the bigger cans are more impressive than quarts, and if you have the room, buy them!
Normally quart versions of a can in top condition will sell for more than a five, but there are the exceptions. Some flat out rare 5 quarts like Polly or Gilmore always bring super money in top or above average condition. The price may not necessarily reflect it, but I think the 5 quart Marathon Endurance can is tougher to find than the quart, but they seem to bring comparable money. I'm curious to see what the other replies are to your query.
Darin