Brian wants to upgrade his MacBook Pro RAID drive and wants the fastest drive possible. Leo says that a Thunderbolt 3 external drive would be the fastest he can get for it. Leo recommends the Envoy Pro EX from OWC. It's also bus powered. But a 6TB drive is over $1,000, so it's not cheap.
Leo went another way though, with a USB-C 8TB drive array and that was much cheaper. Oyen Digital's MiniPro RAID vs USB 3.1 Type C is $99 and he can toss in two Samsung 950 EVOs and he'd have 2 TB in a RAID array. Running RAID 0 (Scary Raid) will be fast and give him the most storage.