I suggest bitcoin because it's secure and fast no need to type any personal info and the transactions are totally free and if you save lots and lots of bitcoins right now you could be a millionaire after 10 years because more people are investing to this crypto currency more countries are starting to use bitcoin.
All well and good until you try to cash out.
How exactly do you intend to convert $1 million in bitcoin to cash without giving out all your personal info.
cashing all 1 million in bitcoin at a single transaction or a single deal would be difficult. but why should we do this? we can cashout small small amounts of bitcoins many time.. bitcoin is still better than gold. gold also have risks while selling huge quantity.