Prices just dropped on Seagate Barracuda 4TB, 5TB and 6TB drives but for overall cost-per-gigabyte the 3TB remains the overall champ. There is a general consensus that the largest/newest size available is more likely to fail than the “tried and true” options, so I’m staying with 3TB for now, but it is not hard to imagine a day very soon when your 5 bay NAS will sport a 24 terabyte RAID 5 volume. So let’s be careful out there.