Most Reliable USB HDD Enclosure? 1 Or 2 Bay Backup Setup?

[BfA]

My only requirement in this is to ensure that my data is safe long term so I don't mind spending more if there are definable benefits. This is only for a detachable USB drive for onsite backup. I'm not looking for a NAS as I will already have this data on existing live HDDs.

I've read many reviews on different sites but it's hard to find out information on the reliability of the enclosures. I would like to find one if possible that will use USB 3.1 Gen 2, but I understand that is pretty difficult since it's so new. This drive will more than likely be kept in a cupboard for months at a time and completely detached from any electronics. If anyone has an opinion on if the 1 bay or 2 bay setup would be better for a backup I would also be very interested in hearing that. I'm not sure of the quality of the RAID that would be offered in two bay. Depending on what enclosure I can find I'll either be using the following two setups. I personally think the 1 bay with an enterprise drive would be easier to manage and more reliable.

1 bay enclosure with 4TB HGST Ultrastar 7K6000 SATA

2 bay RAID 1 enclosure with 4TB HGST Deskstar NAS SATA

Requirements
4 TB (Would be great for 6 or 8 for future proofing)
USB 3 / 3.1
SATA III connectors
RAID 1 (If 2 Bay)
Small & portable


USB 3.1 1 Bay

StarTech.com USB 3.1 Gen 2 (10 Gbps) Enclosure for 3.5" SATA Drives - Supports SATA 6 Gbps

VANTEC NST-370A31-BK Aluminum / Plastic 3.5" Black Standard SATA USB Type-B 3.5” SATA 6 Gb/s to USB 3.1 Gen II Type-A HDD Enclosure


USB 3.0 1 Bay

Rosewill RX-358 U3C BLK – External 3.5" Hard Drive Enclosure – Aluminum & Plastic, Black, SATA I / II, USB 3.0 & eSATA

StarTech SAT3510BU3 3.5" Black SuperSpeed USB 3.0 SATA Hard Drive Enclosure w/ Fan

VANTEC NexStar HX4R NST-640S3R-BK 3.5" Black SATA I/II/III USB3.0 & eSATA Quad Bay RAID HDD Enclosure

Thermaltake ST0020U 3.5" Black SATA I/II/III USB 3.0 Max 5G External Enclosure

Vantec NexStar CX SuperSpeed 3.5" SATA to USB 3.0 External Hard Drive Enclosure - Model NST-310S3-BK

Thermaltake Silver River 5G ST0025U 3.5" Black SATA I/II/III USB 3.0 External Enclosure

ICY DOCK MB559U3S-1SB 3.5" Matt Black SATA I/II/III USB3.0 & eSATA Professional Ultra Slim External Hard Drive Enclosure


2 Bay Options

ICY DOCK MB662U3-2S R1

Vantec NexStar MX Dual Bay 3.5" SATA to USB 3.0 / eSATA RAID Enclosure

Mediasonic ProRaid HUR5-SU3 2 Bay


As well the Samsung M3 4TB Portable STSHX-M401TCB would be a very intriguing option, but I'm not sure of the reliability of the hdd in it and it's also extremely hard to find.