I think I am clear on what to use where for Associations: The label is very specific, identifying the association or relationship between the two specific nodes. A stereotype doesn't normally make sense for associations, since it identifies a kind of association. Examples I have seem is <<include>> for use cases, and identification of the protocol for component associations.
For Dependencies: A label often does not make sense, since the relationship is always "depends on." A stereotype further defines the nature of the dependency.