I Think Btc is Better Bitcoin is one of the very good choices here as its digital currency. You can store your bitcoin even on a piece of paper or use physical wallet. Some rich people who would like to hide some part of their wealth from bank/security accounts. The Swiss bank was a good option to do it but not anymore. The common way is to put cash or valuable goods or commodities (like the art piece, gold, diamond) but those take-up spaces and you need to find safe space to accumulate them.
Good point where we can avoid the taxes we collect in one place virtually, but this will soon be invalid because some countries are starting to be active with the formulation of income tax from bitcoin, we can not always avoid taxes because it is our responsibility since born into the world .
The conjunction with other things is better because the cash can be spent with the smallest nominal cost, but transactions via bitcoin below 100 $ will be trimmed with fixed costs that tend to harm us.