I don’t know why any regular person would buy either of those as an investment. At one time I did own a one ounce palladium coin. I bought it for $980, when palladium was about $850. I tried to sell during the huge spike in palladium. It was going for over $1,900 an ounce then. It took me nine places to find a buyer and the offer they gave me was far below market value. While I made a profit on it, not many precious metal places want it.
I’m assuming you are in Europe with the VAT tax on silver. I’m not 100% versed on what is taxed and isn’t taxed. But I thought if you bought government produced silver coinage it was free of VAT. But I’m not certain not being in Europe. I do know a few people in Europe that buy from Germany to avoid the VAT.