I have a total of 12 HGST NAS hard drives that are between 6 1/2 and 7 1/2 years old. They all run 24/7/365.
Eleven of them are 4 TB; one is a 3 TB. The 3 TB and one 4TB are in my workstation. The other 10 4 TB drives are in my NAS.
None show any signs of aging or failure. One drive got kicked out of the NAS array about 2.5 years ago. I removed it from its hot-swap bay, and plugged it back in. It was recognized and rejoined the array. Other than that, there have been no incidents and no evidence of drive aging or failures. The NAS array is a RAID-6 and is scrubbed for errors once a week. No evidence of bit-rot (or if so, the scrubbing fixed it).
I would not have expected to go this long with zero failures. But I have. So, if you are looking for reliable drives, might want to look at HGST NAS drives.