I won't disclose which GPS I use or how many but all let me put in the destination and push Go!. If I don't like the result I can put in waypoints or change the routing method. But NO GPS I know allows me to select a route from displayed routes.
But I can examine the route it made and on most, change it by either adding waypoints or canceling it and using another route method.
I can imagine some one would not like that and would not buy any GPS made today.