Platinum Axe

Platinum and Gold occupy the same rung, so the answer is whichever ore your world rolled. Neither deserves a second thought once you have the axe made from your world evil ore, which chops noticeably faster for a similar amount of digging.

Pick the harvesting roll. Axe combat is a novelty, since in any fight that matters you will be holding a sword or a bow instead. The only argument for the damage roll is convenience: an axe already in your hand saves a hotbar swap when a slime wanders into your tree line.