Sampled arpeggios would seem to have a very limited application because of tempo and subtle changes in the sequence of notes. Melodyne would probably allow you to tweak them but doing them yourself would be just as fast if not faster.
String runs are far more common and less varied. They will be less likely to be heard as samples whereas arpeggios would shout samples.
My two cents
String runs are far more common and less varied. They will be less likely to be heard as samples whereas arpeggios would shout samples.
My two cents