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Which one is more valuable?
More to the point, which one is the right size?
Most likely issue is a ⅜" axle being too big for 9mm fork ends, in which case some #judiciousfiling of the threads will make things right, assuming it's a QR axle. Don't do it if you have a ⅜" solid axle with track nuts, cutting that down to 9mm will take too much of the thread off to be safe.
This is a Shimano M10 axle (HB-M495, but the HB-M525 is similar) which is turned down to 9mm to fit fork ends, to give an idea of what you want to end up with.
Which one is more valuable?