  Value-based argumentation enhances a classical abstract argumentation graph -
in which arguments are modelled as nodes connected by directed arrows called
attacks - with labels on arguments, called values, and an ordering on values,
called audience, to provide a more fine-grained justification of the attack
relation. With more than one agent facing such an argumentation problem, agents
may differ in their ranking of values. When needing to reach a collective view,
such agents face a dilemma between two equally justifiable approaches:
aggregating their views at the level of values, or aggregating their attack
relations, remaining therefore at the level of the graphs. We explore the
strenghts and limitations of both approaches, employing techniques from
preference aggregation and graph aggregation, and propose a third possibility
aggregating rankings extracted from given attack relations.
