Both are a strong currency, but if you are talking about the future, than I would pick Bitcoin of course because you cant use gold as an online payment method so that will be bad for you later.
You also can see now that the value of Bitcoin is slowly rising and that the using is also rising and that is perfect.
Gold is better option then bitcoin and gold is an investment and for making online payment we have many options available, but when it comes to an investment gold is the best.