Ask HN: What's your favorite small server?

I'm replacing an old system that resembles Frankenstein's monster, one that I have been using as a FreeNAS server off and on for a few years.

I want to modernize the system, and so far my top pick is a Lenovo ThinkServer TS140 70A4001LUX which nets me a system using ECC memory and 4 drive bays (OS would boot off an internal usb connector). The drive bays are not hot-swappable, and a bit awkward, but I can live with that. All for only about $350.

I'm looking for a home FreeNAS box, something with ECC memory, minimum of 4 drive bays (more and hot swappable would be nice-to-haves), quiet operation, enough power to transcode video on demand when using Plex media server.

What are your favorites?