Side-by-side spec and price comparison. Live data from Amazon US.
Western Digital WD Purple 4TB WD43PURZ balances price ($60.00/TB), warranty (3 years), and 180TB/yr workload rating for the best overall value.
WD Ultrastar offers better value at $47.50/TB vs $60.00/TB - a 21% 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.
Western Digital WD carries a longer 3-year warranty vs unknown years for WD Ultrastar. Both are enterprise-grade drives built for 24/7 operation.
WD Ultrastar is the better fit for NAS storage. It uses CMR recording which is safe for all RAID levels. SATA interface is compatible with all NAS platforms including Synology, QNAP and TrueNAS.