I think it used to be the same 4 or 5, but its changing. There are starting to be some other strong players in the game so there's more diversity and strategy needed because of it. Kinda cool.
Used to be the same 5 without any difference all in the same order. At least now there are differences. If the defender buff update goes in soon then we may see even more changing of the guard. I'm excited to see this next update.