reliable single-bay NAS instead of 2-bay NAS?

I want to get my first NAS. It will be used for music streaming to my SONOS system and also possibly storing pics. Video streaming may be a future option.

I have no interest in RAID and plan on adding a separate USB drive for backups.
Given this, is there any reason to consider a 2-bay NAS?
I am tempted to just buy a good, single drive NAS.

I am thinking a Synology would be more reliable than a WD MyCloud.

I am considering a DS115.

If I decide for 2-bay, I am looking at DS215J or...

reliable single-bay NAS instead of 2-bay NAS?