Seconded for Transmission. It's light on features because (as far as I know) it's the only ine in this list that's built to run unattended in a Docker container, with a web interface.
If you're trying to build it all from scratch, sure, but you specifically mentioned docker and there's plenty of high-quality docker images you can use - and it's no harder to use a qBittorrent docker image than a transmission docker image.
I'm not even going to argue that the qBitTorrent docker image is technically easier as it has less to configure, it's all one command at the end of the day.
I used to use it but then I just downloaded aria2 (what motrix is using) and it's as fast as motrix with a little bit of configuration. aria2 supports both direct downloads and magnet links, it's a command line tool though