OK, I sense cross-purposes here. You're asking "what would be the most interesting and intelligible form of positive alien contact (in human terms)", and Zack is asking "what would be the most probable form of positive alien contact"?

(By "positive alien contact", I mean contact with aliens who have some goal that causes them to care about human values and preferences (think of the Superhappies), as opposed to a Paperclipper that only cares about us as potential resources for or obstacles to making paperclips.)

Keep in mind that what we think of as good sci-fi is generally an example of positing human problems (or allegories for them) in inventive settings, not of describing what might most likely happen in such a setting...