It's easily the PSX version unless you're playing on the PSP and can get that nolag patch to work.
Now if you can it still might be the PSX version that you like more. If you like flowery olde English style dialogue you go with WotL. If you prefer mostly "normal sounding" dialogue with a silly translation here and there (not very many of these) you go with the PSX version.
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No problem!
This is a cute and pop genocide of love!