Who wins?
Cow vs Wither
Cow wins 54% to 46%. 27 more put them in the same row. From Minecraft Mobs Tier List. Pick a side.
TinyFalcon on Cow: the most useful mob early game, leather for books and steak that keeps you fed
crispy_badger_46 on Wither: summoning it in the Nether and fighting it for the beacon is the best endgame project in the game
Minecraft Mobs Tier List: the full ranking