ponderings from the dairy aisle

Most of the time (where I shop), milk comes in plastic containers. Occasionally, it comes in the waxy cardboard ones instead. Last night I actually had a choice, and realized I don't know which one is more green. Plastic can be recycled (good) and the cardboard can't, but I have the impression that producing the plastic container is more destructive to the environment -- and, of course, you also have to factor in the costs of recycling. Trash in a landfill also imposes a cost, and means that cost of production is borne entirely by one use. Overall, I don't know which one is less bad.

Which would you buy?