These days, if you’re playing a game with multiple versions, there’s usually one specific version you want. For pre-Crash games, if there’s an arcade version, most of the time, it’s the one you want. After the Crash it becomes less definite. Super Mario Bros. at home is a much more playable game that the arcade version. Vs. Super Mario Bros., which is hungry for those quarters. For games like Smash T.V. though you still usually want to play the arcade version.
The arcade and PC Engine CD version of Gradius II though are a much closer call. In a couple of places this home version is actually slightly better, or slightly harder, than the arcade original. It also contains an extra level that’s missing from the arcade.
Inglebard Gaming on Youtube has played through both games entirely and shows them to you side by side, so you can decide for yourself!
Gradius II Arcade vs PC Engine Super CD (Youtube)