I wouldn't choose any of these. Gold goes down and I predict that it will go even lower. Bitcoins are not stable and who knows what will be later. If we are talking in depositing in some kind of materials for some years I would prefer diamonds. I don't say that their value won't fall, but I'm sure that they won't fall as fast as gold and bitcoins.
You need to look at the big picture. I would say 50% gold and 50% bitcoins. In 10 years, that 50% in bitcoins will worth A LOT OF MONEY, because of mining diff and distribution/adoption.