The Samsung EVO 850 SSD may only use the SATA interface, but it’s pretty much as good as it gets for a SATA SSD, offering 549.6MB/sec reading and 527.8MB/sec writing. The latter in particular is excellent, as many SSDs are considerably slower for writing than reading. Considering that SATA 3 can only offer 600MB/sec under normal conditions, you’re getting just about as much bandwidth as is realistically possible.
The Seagate BarraCuda is specified at 220MB/sec reading and writing, and it delivers on the money for reading, with just a little drop off for writing. As conventional 7,200rpm hard drives go, this unit is also top of its performance game.