My experience, I sometimes buy gold coins to make jewelry. I do that because at least here in Belgium, there's no VAT on coins but there is VAT on the other forms of gold that are more commonly used for that. For professionals it's not a problem because they pass VAT but for an individual it's a 20% difference. Also I'm in Antwerp so it's really easy to just bike to a place that sells gold if I want to.

In my case I buy old French 20 francs coins as they are quite "cheap": 1% above spot price of their gold content (they are 90% gold).

Other more recent coins, like Chinese or Canadian ones, sell at a much higher premium (17%, 20%) so I always wonder a bit who they are for. It's unlikely they can be resold for that much of a premium. At least the shops I use just buy them for their price in gold.