Verdict

Both are CMR drives suitable for NAS. The ST16000NM001G has the lower measured failure rate (0.54% vs 1.73% AFR), making it the safer long-term choice.

MG09ACA16TE ST16000NM001G
Capacity 16 TB 16 TB
Recording tech CMR CMR
RAID / NAS safe Yes Yes
Class Enterprise Enterprise
Spindle speed 7200 RPM 7200 RPM
Cache 512 MB 256 MB
Noise (idle) 20 dB 29 dB
Fill Helium Helium
Interface SATA SATA
Failure rate (AFR) 1.73% 0.54%
Price / TB $50.62 $33.65

Highlighted cells mark the stronger spec for a NAS build. Failure rates from Backblaze Drive Stats where available; $/TB shows once live prices are wired.