Which is better from a collectors point of view, collecting US or JPN versions?
There are a lot of games that had way less US releases than JPN releases, so US versions are considered more “rare” than JPN ones and therefore are more collectible. Normally, US versions are more expensive, but that’s a matter of availability because you will pay about the same for a US version of an older (common) game. However, finding US versions of certain games like Ninja Master’s can be difficult which adds to the price. A real collector would go for a complete CD collection with all JPN and US titles anyway.