There are stand up mid arm quilting machines and sit down ones. Stand up ones generally have between 10-16 inch throat. You can do free motion, ruler work or pantos on a stand up one.
I see a great many sit down machines and 'Little foot' machines in sale groups, Most say they are upgrading to a larger machine and frame.
I have a used HQ16 stand up machine. It is considered to be a mid arm machine by many.