I really like Seq. It supports tons of log types, including GELF, which means you can configure your docker hosts to send all container logs to Seq with just a couple lines in Docker’s daemon.json file.
Setup is pretty simple as a docker compose stack containing the Seq container and a container for ingesting each of the log types you plan to use.
If you wanted to try it out, I’d recommend setting up Seq with seq-input-gelf and seq-input-syslog, and setting up nginx to send access and error logs to syslog as detailed here.
Have you tried to ssh into it?