Which Micaiah +atk - spd , +atk - res

She doesn't have much speed anyway so i think the first one is much better, less res will mean less dmg from iceberg or glacies

-Spd (and +Atk? lucky you)

She is slow anyway. Won't ever double anyone. Lowering the speed also doesn't get her doubled by anyone who would not double her otherwise and who she actually fears.

Meanwhile, Res is an important stat for Micaiah. That is directly related to her bulk in enemy phase, her Iceberg output and her ploy potential.