Gold bars or coins for selling

As far as defensive investments go, many like to put money into physical gold and silver to hedge against market negativity or bearish sentiment and expectations.

What is your preferred physical gold investment (Bars or Coins) and size, for the purposes of selling back or potentially using for trade, should the markets fall into collapse as many economists are expecting with the current overinflated bubble we are experiencing?

Any thoughts are welcome and Thank You!