Ok... at this point, Wilson US Open balls have the majority lead at 22.83%. They tower over the next closest "listed" competitor at almost 2:1. However, "Other" has 20.65%. Granted, that probably comprises many other brands/models, however, there have been few comments (other than "Slazenger") about what those balls may be in particular.
If the forum had allowed, I would have listed more choices when I created the poll. Basically, I just went to TW's site and listed the available balls in order.