Let’s say you have a block of splintery hardwood that is already cut to final length & width and you just want to clean up the surface by taking off maybe .01" or .02". Here’s the toolpath:

The top corners need to be perfect - no chipping/splintering as the bit makes the final pass around the top edge. What would you use for the best chance of success - 1/4" Upcut or 1/4" Downcut?