Waiting for you.
I say in line and waiting for you.
the people around here who say “on line” are the same people who say “warsh”. so… teachers and adults who have been in St. Louis too damn long.
“waiting on you” is more common. Used by the Warsh parents as well as their children and about a third of the kids who have lived here all their lives but do not have warsh parents.
Think of “It’s A Small World” at DisneyWorld/Land. You wait for far longer than you spend on the ride itself.
Thus, in a sense, the line IS a ride.
And you get on and off rides, do you not?
Yeah! Preech on, brother! 
I say “waiting for you” and “waiting in line” (or “waiting in the lineup”). I tend to say “lineup” rather than “line” when referring to the noun: “There was a huge lineup outside Honest Ed’s when they were giving away the free turkeys.”