Maintenability (maintenance & troobleshooting manual, components availability, support team competent and reactive).
Proof of use (videos/photos of produced items ; even better : displayed in a local shop).
End to end software solution. Either developped by provider or externally supported.
Build volume, support material, wifi connectivity, limited status readings on the machine, automatic bed tramming (calibration), multimaterial/multi colour.
Non specific consumables (compatibility with an open-source standard filament-spool would be even greater).
Safety features (enclosure, air recycling not necessary but appreciated).