Argument comparison or argument attack?
My opinion:
The attack metaphor is a better characteristic of defeasible argumentation and seems to be more fruitful than the comparison metaphor.
? The attack metaphor seems to be the more general. E.g., undercutters are harder to explain using the comparison metaphor.
? Argument defeat is normally the result of an asymmetric relation on arguments (e.g., undercutters and rebutters), while the comparison metaphor naturally starts with a symmetric relation on arguments (viz. argument incompatibility).
? The comparison metaphor implies the separation of argument construction on the one hand and comparison and defeat on the other. This separation is however not required and seems to be an artifact of the comparison metaphor.