Interesting thoughts. I've never heard of most of these bands, so my opinion is flawed at best, but I think you should first define what it is you are trying to define?
Objective criteria in music makes for interesting cocktail banter but poor conclusions. Record sales? Influence? How does longevity fit? Since this is about American bands, it seems the Beach Boys did the most to define America in their songs.
Turning this around a bit, what would someone from England or the continent pick? My guess would be Beach Boys.