I want to try installing LibreELEC for the first time on my parents old streamer: Xtreamer Ultra HTPC Mini-Itx (Wiki)
Which version is mostly recommended from the list via "USB-SD Creator"? raspberrypi 2/3? raspberrypi 1? generic Invidia (sadly onlu 64bit option available)?
No idea why you would want to install a build for a Raspberry Pi onto a Intel x86 based machine. It'll never work as those are totally different machines.
The only option would be the Generic build. I recently installed successfully LE 9.2.3 onto a ION-1 + Nvidia machine, so there is a chance that the Xtreamer will still work. However... If your Xtreamer is a 32bit machine, then all attempts will fail. LibreELEC is all 64bit only for x86 today.
The Wikipedia page that the OP linked to says the Xtreamer Ultra uses the Atom D525 - that version of the Atom is 64 bit capable and since it uses ION graphics (but I think the first version) then it shouldwork, based on the report from Klojum, above. If it is the second generation Xtreamer Ultra with the Atom D2700 then that uses later Nvidia graphics and would proably run LE without issues.
It should run, and no harm in trying..
