I had been writing custom queuing systems for many years for many applications
https://www.bufferbloat.net/projects/bloat/wiki/Wondershaper_Must_Die/
This does not mean all the design choices for cake were right. I have been collecting input on how to improve it over here:
Including, sigh, the often requested feature of a strict priority queue.
Cake is also intensely programmable (see the qosify project), and there is another great project called cake-autorate that uses active measurements to make starlink & 5G’s latencies less awful