Pros: Durability, preconceptions that the beer tastes better from steel, highly conductive, cheap when used.
Cons: Heavy, high scrap value, home brewer's delight, expensive when new.
Pros: Light-weight, stackable, made in California, will not be stolen by devious home brewers, reasonably priced when new.
Cons: Misconceptions about taste, not as cool looking as steel, slower to cool down, cannot be turned into a brutus brew system.
What do you think? Plastic or Stainless?