Well, BP is the only way to have accurate measurements. That’s why it is bone-pressed. However, when taking into account visual perception and NBP, things are a bit different… But ultimately, BP is how we compare statistical gains.
Now, certain people have bigger fat pads than others. Why? I’m not entirely sure yet. Me, for instance, I have a 1” fat pad and I’m a thin athlete (165lbs, 6’ tall). I am not fat at all and I body build, I may in fact have too little fat on my body. Where does that 1” fat pad come from? Who knows, but I wish it wasn’t here because it takes away from NBP.
For me, I consider real gains to be the NBP appearance and gains (as I believe you are saying). However, to remove ambiguous and inconclusive measurements, BP is the way to go… regardless of the fat pad.