There are plenty of options in the 5 and 1 oz size. Although the 10 oz and up is where you get more bang for your buck.
I stack silver in several different forms but my favorite is all of the various world 1 oz rounds. I pay a decent premium on some but many are priced lower than us silver eagles. Today I have about 70 different designs. Fun to look at. For investment I have all size bars from 1 g up to 100 oz. I really like silver in just about any form.
Best to collect American Silver Eagles, normally they sell for more and the resale value is more as well!
My preferred right now is my local source of modern commemorative silver dollars that I get for only about a 10% premium.
You forgot Krugerrands ion your list my LCS sells these close to spot like it’s gold cousin a popular one to stack.
If you are collecting and storing metals, thinking someday you may have to use them to function/survive, then you should have from the lowest kind ( 1/10 oz) to 100 oz. or more. Gold from 1/10 oz ( most important) to what ever higher you can afford. If the world conditions require you to use them, you can "show"/use for your needs. I like the 90% silver mercury dimes myself and have full tubes. A local says he has 1000 of them for sale , but I haven't seen them yet.
Since I started stacking ten years ago I have found that 90% has low premiums and is easy to buy and sell. I don’t worry about counterfeiting with it and you can find good deals if you shop around.
I always enjoy these threads to see what everyone likes and buying. Started my coin collection when I was 8 years old in 1970. For me, it's American Silver Eagles. I like the look, heft and size of the coin. I pay cash for mint sealed rolls of 20 from my local coin shop. As others have said though, the ASE definitely has a premium over other silver options. My LCS is 20% over spot.
I buy various slabbed silver MS69 & 70 issues to stack. Got a MS69 Britannia for $41 recently. Also like the Mexico issues.