The reliability varies quite a bit from model to model regardless of vendor. While Google long ago used the cheapest consumer HDD, they haven't for over 6 years. They buy server-class (also called nearline) drives from multiple vendors. Every other year, some drive model will have a design problem that leads to early failure. At that scale, it's more important to spread out across multiple vendors and models to mitigate that model-specific failure so it doesn't become an epidemic.
HGST tends to build their consumer drives by cost reducing their server-class designs. WD and Seagate tend to design consumer and server drives independently but use them both for introductions of new technologies. Toshiba hasn't had server-class drives until just a few years ago when they attempted to scale up their consumer drives into something more reliable.
There are lots of subtle effects that can affect what gets reported as failure rates. Many, many times the failure is a read failure and that sector is lost but the a write to that sector will force a reallocation and the drive will be perfectly fine. Contrary to common belief, a few (~15) bad sectors on a drive is not an indicator that the drive will truly die soon. With the bit patterns being so dense nowadays, sector failures are inevitable. That's why each drive is tested by the manufacturer and given a permanent table of known bad sectors.
Bottom line: if you want rock-solid drives, HGST is expensive but well built. Seagate is nearly as good and has some other useful features (security features, etc) at a slightly better price.