For the most part, the drive failure rates between manufacturers are equal over time. Every manufacturer has a bad model, bad batch, bad firmware, or something else along the way.
In terms of RMA, we've found that Seagate is the easiest to get replacement drives from. They consistently send the same model or better back. We had a few 500 GB drives that we sent in with 32 MB cache, and they sent back a newer model with 16 MB cache, but it was a significantly newer drive, so it was about a wash.
HGST is absolutely terrible with RMAs since they were purchased by Western Digital. We sent in several 30-day-old drives and got back drives that were a different model and were at least 8 years old (with about 50% of the I/O speed). We've pretty much stopped buying HGST as a result.
Western Digital is only slightly better than HGST with RMAs. They rarely have the right model drive in stock. They often send Blue drives as replacements for Black or REs. We've pretty much stopped buying Western Digital as a result.
We haven't had much experience with Toshiba yet, as they are still pretty new. For a while, they were just selling rebranded HGST. I think they're finally starting to develop their own drives, so we'll probably mix in a few if they start selling at attractive price points.
