I'm guessing either a Jounin or Genin is most preferable for the sake of character interaction with the plot?
Or rather, I suppose I should be asking if there are any particular ups or downs to going with a Chuunin instead? That seems like a good middle-ground and opens up some more options in a village like Sound. Also means I might not need a full team of other players to really get into things right away, since the flexibility doesn't pigeon-hole them as badly plot-wise.
Edit: Mainly, I noticed we already have basically exactly enough players for a single Sound team, so I figure a Chuunin is the best fit.