Which set has the largest capacity?

Remember that 1 gallon = 4 quarts = 8 pints = 16 cups.

4 quarts 12 cups = 16 cups + 12 cups = 28 cups

12 pints 2 cups = 26 cups

2 gallons 1 cup = 32 cups + 1 cup = 33 cups

So 2 gallons 1 cup has the largest capacity.