Personally, I'd lean towards the ODROID-H4 Ultra. I've been using an ODROID-H2 on my desk running Linux Mint (Ubuntu) for a few years, and it's been great. We also sell systems like the YouYeeToo x64 mini PC and we've sold Beelink and other pre-built Mini PCs in the past.
However, I really like the customization and expandability of the ODROID-H4, and the ability of it to run any mainline operating system you'd like. Plus, it can support up to 48GB of DDR5 RAM. With the other mini PCs, what you bought is pretty much what you are stuck with as they don't have much flexibility.
I'm currently building an ODROID-H4 Ultra into a Nextcloud server for the family with 24TB of redundant storage. I'm using the Mini-ITX adapter for it so it can go into a standard Mini-ITX case with hot-swappable drive bays.
https://ameridroid.com/products/odroid-h4-h4-h4-ultra
https://ameridroid.com/products/h4-mini-itx-kit
Bo
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