For the Auto Fill option I like choosing Host here. But when I chose Base Domain, I got more choices. I want the best of both worlds. I just want my Host choices first and then the remaining Base Domain choices tacked on at the end.
By the way, you will notice the extra small font in the pop-up menu in the middle of the screen. Also there ought to be a help button as a third button and pressing it will bring us to the familiar web page that explains all this.