Definitely 2 M.2 slots please*. I'm happy with one NVMe and one SATA, the data drive doesn't need to be so fast and I'm told the real world difference isn't that huge. Happy to lose space hogging SATA power & data cables, and heartily vote for a reduction in the power cabling setup while I'm at it. * Particularly AMD ITX that most only have one on. Asrock have 3 M.2 slots on their super tiny Deskmini for goodness sake!