Side-by-side spec and price comparison. Live data from Amazon US.
WD Ultrastar 14TB SAS wins on both price ($23.57/TB) and warranty (5 years).
WD Ultrastar offers better value at $23.57/TB vs $42.46/TB - a 44% price difference. Factor in warranty length and workload rating when the price gap is small.
Mixing drives of different models in RAID is not recommended even if capacities match. Different firmware, error handling and seek patterns can cause rebuild issues. Use identical drives within the same RAID group for reliable operation.
WD Ultrastar carries a longer 5-year warranty vs unknown years for WD Ultrastar. Longer warranty typically correlates with manufacturer confidence in reliability.
WD Ultrastar is the better fit for NAS storage. It uses CMR recording which is safe for all RAID levels. SAS interface requires a SAS HBA or SAS-capable NAS.