Choosing the right size for a triangle powder puff largely depends on your personal preference and the areas of your face you intend to apply makeup to.

1. Large Triangle Powder Puff: These are ideal for applying loose or pressed powder over larger areas of your face such as your forehead, cheeks, and chin. The larger surface area allows for quicker application and even distribution of the product.

2. Mini Triangle Powder Puff: These are perfect for precision application of powder, especially in smaller, hard-to-reach areas like under the eyes, around the nose, and the corners of the mouth. They can also be used for applying highlighter or contouring products in specific areas.

3. Small Triangle Powder Puff: These offer a balance between the large and mini sizes. They can be used for both broad application and more detailed work. They're great for everyday use where you might want a bit more control than a large puff offers but don't need the precision of a mini puff.

Remember, the size of the puff doesn't affect the quality of the application, but rather the speed and precision with which you can apply the product. So, choose the size that best suits your makeup routine and the level of detail you prefer in your application.