What I left out in my rush to get out of the office after finishing this post last night at 6pm was a very important statement of opinion re the below debate.
I think that each of these cities and their respective music scenes are intextricably intertwined. You very rarely can foster your band in LA and only be present there...you must be involved with the New York scene as well (see Local Natives, an LA band signed to a New York label with a New York PR firm). The same goes for New York bands looking to hit it big on the West Coast.
In other words, being successful in the U.S. indie scene demands a presence in both scenes on both coasts, and bands that manage to connect with LA and New York audiences have been the most successful over the last few years.
Therefore, below is simply my heartfelt opinion about, if I had to choose, which music scene I delight in more and why.