I would prefer to have both, physical gold is good insurance with long history of recognition as money all around the world while with bitcoin you have the chance to take part of a new paradigm shift taking place with potentially incredible upside, but arguable the risk of going to zero also, if only allowed to pick one I would first ask what time horizon you have and what is your goal with your investment, can you handle large swings bothways and potentially risk your capital?

I think they both have an own important place in everyones investment portfolio :)