I think 36" is a happy medium, works well for sitting and standing and provides enough room underneath for your sump and skimmer. It may also be wise to make sure you can't see the light bulbs in your fixture when you sit down, this can be annoying if you can see them.
When I sized my tank and stand I measured the distance from the floor to my arm pit and made tank height + the stand height = to that. I can now stand comfortably with my arm in the tank, with no stools or crouching required
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