Measuring by weight is by far the most accurate method. It doesn’t matter how packed-together your ingredient is, 100 grams will always weigh 100 grams. The other beauty of measuring by weight is that you can measure every ingredient using the same method, and you only need one tool to do it: a scale!
Grams are my preferred unit for weight measurement. If you grew up in the US, I empathize with you about feeling unfamiliar with the metric system. However, grams are the smallest form of weight measurement, and therefore the most accurate. Don’t fret! As long as you can read the numbers on a scale, you can easily measure in grams.