Measurements are the best way to see just how much change is occurring to your physical features. For this reason, it would be recommended to conduct Arm, shoulder, chest, waist, hip and thigh measurements to get the best data tracking.
This method of tracking would be least recommended, simply because it is not taking into account body composition. You could weigh 130lbs and still be lacking the proper muscle percentages.
Body Fat Percentage
This would be the best way to know you are losing fat and gaining muscle. 200lbs at 10% body fat looks a lot different than 200lbs at 35% body fat. as a general rule we would like to be between 10-25% body fat for optimal health.