Go with true level wherever you can, and in this case it's probably warranted too. If levelling the desk poses no optical distractions, then go ahead.
But there are cases where it might be better not to level: if you have existing cabinetry, windows, doors, trims etc.. where it would become noticeable that you have a 1/2in offset, you can go with the tilt or meet halfway for optical reasons.
Storing spheres, cylinders, card stacking and filling your coffee to the brim of course could forestall this option. Reminds of the carpenters' expression for level: "dead balls".
On the other hand, if levelling the desk highlights the tilt of other finishings in the room, then you could opt to apply some tilt or meeting half-way. It's not uncommon to apply gradual corrections when spacing out / levelling spindles, wall decorations, window openings, trims.