I do not think that you can even really compare them with each other, they are both very different the gold one is physical and the bitcoin is digital and has another target too, I think we cannot compare them..
But if you're an investor then can consider it both as different assets and compare your investment returns after some time right? Whether it is physical or online it doesn't matter in investing but what is important is how much profit we made over the time is very important in investing. So think we can compare both and I like both of them because both got different advantages and invested in both.