Probably the Odyssey Blue, which uses a Celeron rather than an Atom CPU. I disabled the fan so it is silent, and the temperature stays very stable (and pretty low). It’s a wonderful device. I’ve programmed the Arduino and use it with Home Assistant (serial sensor). My Odyssey Blue is virtualised using Proxmox and also runs OpenWrt (router), Home Assistant, UniFi Controller, Plex, Transmission, CUPS, SAMBA and more. It still has plenty and ram and CPU left too, if I only I could think of anything else I want to run on it.