Every collector is the boss in his/her collection, i.e. he/she collects (or stacks) according to his/her taste and preferences. Having said so. It is other matter the resale value of the collection and how liquid is the collection. If someone is only interested in playing "the silver price", so it makes sense only stacks silver bullions bars/coins. Everything else has a large premium in the price.

I like "historical coins" because they tells "a story". They were minted because there was a need for their usage, not for "selling them to collectors", as modern commemorative coins. However, here we are talking with large premiums in the major part of the cases and the problem with counterfeits and fake coins, which is a "cancer" in the field.

Well these are some of my thoughts in the subject of collecting.