I am currently running

• Nextcloud: slow, but great for Calendar or Notes
• Gonic
• Airsonic Refix
• transfer.sh
• FileBrowser
• Conduit
• Cinny
• Mosquitto
• Prometheus
• Grafana

The last three are quite niche. I use Prometheus + Grafana for Monitoring the Pi itself and for displaying MQTT Stats. Since upgrading to SSDs performance is actually quite good, especially when taking power usage into account.