Newspaper advertisements from the 1870s show that in different cities, different men were given top billing. Initially Ned Buntline, as the author of the play and famous dime novelist, was mentioned first. Sometimes Giuseppina Morlacchi, the world's most famous danseuse, got the large print.
Up north it made sense for the former Yankee soldier Bill Cody to be mentioned first and south of the Mason-Dixon line it was often the Confederate scout who proved to be the draw.
As far as Buffalo Bill and Texas Jack were concerned, this was a true partnership. They made decisions together, split the income equally, and always had each other's backs. They were, as Buffalo Bill would later write, "Pards of the Plains for life."