pfSense

HFSC support priorities just as any other scheduler:

hfsc  Hierarchical Fair Service Curve.  Queues attached to an interface
           build a tree, thus each queue can have further child queues.  Each
           queue can have a priority and a bandwidth assigned.  Priority
           mainly controls the time packets take to get sent out, while
           bandwidth primarily affects throughput.  hfsc supports both link-
           sharing and guaranteed real-time services.  It employs a service
           curve based QoS model, and its unique feature is an ability to
           decouple delay and bandwidth allocation.