If only one NES ROM should be kept, which one should I choose?

[fyngd]

Castlevania (USA)
Castlevania (Japan)
Castlevania (Europe)
Castlevania (Micro Genius)
Castlevania (Virtual Console)
Castlevania (GameCube Edition)
Castlevania (xxxxx Collection)

[Hiccup]

if you mean in terms of which to play, USA is generally a good pick for NES, because it'll be in English (if you want that), and it'll be 60Hz unlike European/PAL versions which will be 50Hz (afaik). As for if you want one of the (usually digital) rerelease versions (VC, GameCube etc), it depends if you want to play the game as it was released back in the day, or if you want the modern day improvements (bug fixes, epilepsy reductions) that they might have made.

[Braintrash]

The Japanese one. Totally.

[fyngd]

if you mean in terms of which to play, USA is generally a good pick for NES, because it'll be in English (if you want that), and it'll be 60Hz unlike European/PAL versions which will be 50Hz (afaik). As for if you want one of the (usually digital) rerelease versions (VC, GameCube etc), it depends if you want to play the game as it was released back in the day, or if you want the modern day improvements (bug fixes, epilepsy reductions) that they might have made.

Thanks buddy!

[fyngd]

The Japanese one. Totally.

Thanks buddy!

[Hiccup]

Yeah actually, the Japanese version can often have the same advantages as the USA one (English text, 60hz), but with bennifical differences to the USA version (e.g. less censorship).

Not sure if that's the case for Castlevania, but there's some info on version differences here https://tcrf.net/Castlevania_(NES)