It all depends on where else you plan to eat. If you just get the QS plan, it might be a little easier to get full value, but then it depends on how many meals you plan to eat with the snacks. For every meal you use snacks for, you need to find a time to use that meal credit elsewhere. If you use QS credits to get festival snacks, you lose the alcoholic beverage, but the snacks are usually expensive enough to still make this a good value.
So, as with any other time you might want to use a dining plan, FIRST plan where you want to eat and then do the math.