In particular the Hardkernel ODROID-H2+. It's got 2x2.5G ethernet ports (and optionally 4 more), M2/nvme, 2 SATA, and 2 dimms (max 32GB ram).
It's not particular power hungry (max TDP of the J4115 is 10 watts), if your needs change the extra ram could be quite handy.
Should be fine for router duty, firewall, network service, plex/kodi, even light NAS duty. It's got way more CPU than the RPI and clones, avoids ugly things like network or storage over USB, yet generates minimal heat/noise.