Personally I like red peppers better than green peppers in most meals. Red peppers have more sweetness to them. But, when you're making stuffed peppers, green peppers are the better choice. They're frugal, which is helpful for your budget. And since you have so many other ingredients in the recipe, you don't want the sweetness of the red pepper competing with the savory meatball mixture. Of course, you can use either, but if you are worried about your budget, green is the way to go.