I recommend common government-minted one-ounce bullion coins. For example, the Silver American Eagles and Canadian Maple Leaf coins. These coins are common, highly recognizable, composed of .999 fine or better silver, and are not prone to high premiums like rare uncirculated early US silver coins. These coins do generally carry a $1-3 premium per ounce, but the free market has determined the benefits of these coins are worth this small premium. These coins are accepted world-wide as silver bullion, and you can be sure you will have no problems conducting trade in these coins if the need arose. Government-minted coins are more easily proven genuine than a ten+ ounce bar of .999 silver of lesser-known mint origin. Coins minted by governments like the American silver eagles and Canadian maple leaf coins are also legal tender, at $1 USD and $5 CAD respectively. While we are currently in times of such currency devaluation that these face value of these coins has declined over 98%, one might be able to imagine future scenarios where 1 US dollar or 5 CA dollars would somehow be worth more than 1 ounce of silver. So, the added novelty of being legal tender, and the fact that they are made by government mints to exacting purity and measures make these coins attractive to any silver buyer.
Pre-1964 US 90% “junk” silver coins are also a good choice. Junk silver is an informal term for any silver coin in fair condition which has no numismatic or collectible value above the bullion value of the silver it contains. The term junk silver usually refers to US quarters, dimes, dollar and half-dollar coins minted before 1964. These coins are made of 90% silver, mixed with (usually) 10% copper to harden the coin so it lasts longer in circulation. One a dealer level, junk silver coins generally are bought in bags of $1,000 face value. They are sold based on the value of the silver they contain. A $1,000 bag of junk 90% silver coins will contain over 700 ounces of pure silver. On the retail level, junk silver coins can be bought in any quantity, although it is often most convenient to buy based on increments of face value or in rolled form. Junk silver can usually be found with little to no premium, and have the added upside potential that some years or mintages are or will become rare and more valuable than their silver content alone. They are also alloyed with copper so they are more durable, and are thus ready for trade and circulation should the time come that our day-to-day transactions are conducted in silver.
.999 Fine Silver bullion bars are a great way to own silver at little to no premium. Solid bullion silver bars of .999 fine purity are a great way to buy silver. I recommend you buy 10 oz Silver Bars that are clearly marked for purity and weight, and are from a well-known and respected mint. Never buy silver-plated bars; you only want solid .999 silver. Anything marked “100 mills” or similar is a cheap metal bar that has been plated with a minimal amount of silver. Some examples of well-known silver bar producers are Engelhard, Johnson and Matthey, Heraeus, Sunshine Mint and Apmex. Bullion bars generally carry the smallest premium of any form of physical silver, and are the choice for stackers who are trying to maximize the number of ounces they hold. In fact, 100-ounce and 1,000-ounce bars can sometimes even be bought from large wholesalers at spot price with no premium at all. However, I do not suggest buying 100 oz silver bars unless you already hold at least a thousand ounces of silver, so that you do not have more than 10% of your entire stack in any one single piece of physical silver. The market for resale and trade for such a large bar of silver will be severely limited compared to one-ounce coins or ten-ounce bars, and you do not want to be stuck trying to buy a loaf of bread or bag of rice for your family when all you hold is a 100 ounce bar of silver.
Generic 1 oz Silver Rounds are also a popular choice. If you are stretching your silver investment dollar as far as you can, you can squeeze some extra value by purchasing “generic” 1 oz rounds. These are not considered coins, because they are privately minted instead of government-made. You can usually buy silver rounds at a very low premium over the spot price. You want to purchase .999 silver 1 oz Silver Rounds that are clearly marked for weight and purity and come from well-known mints.
You may find that a mix of generic rounds, government coins, bullion bars, and junk silver to be ideal. This will give your physical holdings some diversity and flexibility if the time comes when you need to sell your silver or use it to buy the things you need. Avoid buying commemorative coins, decorative items, and other collectibles, all of which carry large premiums and have limited resale markets.