Ask a coin dealer whether Eagles beat bars and you will get a confident yes.
Ask a bullion dealer the same question and you will get an equally confident no.
Both of them are telling you what they have in inventory.
The actual answer is not a preference. It is a function of one variable that almost nobody raises during the sales call: how you plan to get the money back out.
That is the whole thing. Everything else is decoration.
Let us do this properly, because the difference between these two choices can be worth several thousand dollars on a mid sized retirement account, and it compounds in ways that are easy to miss.