Gold will not bring big returns like bitcoin so it's up to you, if you have little money and want to multiply many times, investing in bitcoin will be a better choice. I prefer to invest in bitcoin because it has the potential to give me a big profit but most importantly the purchase price, if you can buy it at a low price, the higher the chance of getting a profit. So now is the time to buy if you want big profit.
It is true that returns on Gold investments are very low compared to Bitcoin in historical context of last 15 years but they are more or less stable whereas due to volatile nature of crypto market investment in crypto is not good for passive income. I think the best strategy is to diversify investment among stocks, commodity, forex and crypto markets to minimize risk and generate stable income.