I am looking for a 4TB backup hard drive and plan to use it externally with a SATA-USB adapter. Later, I intend to buy another one and put both into a home NAS system like Synology. Therefore, the main factors to consider are reliability, noise level, and NAS compatibility. Currently, I’m thinking about WD Red models available in stores here: WD40EFAX ($130), WD40EFPX ($140), WD40EFZX ($150), and WD4003FFBX ($170). Which one would be the optimal choice?