Most reliable option for external backup drive on Win 10 PC

Hi,
You can purchase Samsung, Crucial, A Data, Seagate, Western Digital, SSD external harddisk or other normal external harddisk. 3 years of warranty is fine/available for them.

"Most reliable" would likely be a NAS box or computer with RAID 1 and a hot spare, backed up to the cloud.

If cost is more of an issue to you, I'd look at a Seagate or WD external drive, paying attention to the warranty.  Better yet, buy at least two and alternate between them.

VERY important is to not have the backup drive connected unless you are actually doing the backup.  Ransomware can encrypt the backup drive if it is connected.

I'd use two drives and rotate them on a daily basis.  If one drive fails then the second one is available.

It doesn't matter which drive we recommend.  Drive failures occur even in the most reliable of drives so having a second and using a rotation policy gives better insurance against data loss.

I agree with CompProbSolv. Get a simple 2-drive diskless NAS like Synology:

Diskless System Desktop NAS | Newegg.com 

Then buy two 500GB drives and plug them into the NAS. That should give you a good, simple backup system that can withstand the loss of one drive without losing any data. You can just take out the bad drive, buy a replacement and plug it in and it will start filling up with a copy of the data from the other drive that's still in the NAS.

A more expensive alternative is to use a service like CrashPlan, which does real-time encrypted backups to the cloud and keeps historical track of data so if you want to restore a document but you want the version from 6 months ago, you can just navigate to that file on that date/time and download it. Like I said, it's more expensive in the long run because it's subscription-based, but it can be on all the time, and you don't have to worry about ransomware, and you don't have to worry about failed disks or anything.

I'd want three drives used in rotation, two identical and one from a different manufacturer.
None of them an SSD unless the drives were enterprise-grade SSDs.  If the drives were spinning magnetic drives I'd want them to be enterprise-grade drives and none of them to use shingled recording.

I'd also want the backup software to include redundancy in the backup so that if sectors in a backup went bad, the software could reconstruct them.

i have an usb 3 disk drive dock   from startech
1 drive :  USB 3.0 SATA Hard Drive Docking Station - HDD Docking Stations (startech.com) 
more :  HDD Docking Stations (startech.com) 

then you can buy sata drives - rotating or SSD as much as you want

As mentioned earlier, I'd also use a NAS and a cloud based service where you can old restore old versions of files if needed. Don't care too much about warranty, that is only good to get failed hardware replaced, which usually doesn't cost much anyway. Warranties don't include your data should the hardware fail.

I would be wary of using a SSD as a backup target for two reasons...

1 Endurance, The endurance is rated in drive writes per day, for normal use you don't get anywhere near that rating for backup you do a whole drive write per day. TLC is probably about 0.8 DWPD but for QLC that may be as low as 0.1 DWPD so a 5 year warranty drive will wear out in 6 months.

. Performance. The write buffer of a TLC or QLC drive is a small amount of fast performing SLC flash, write performance is excellent until this cache is filled, then it drops to slower than a HDD. Look at the sustained write performance graph in https://www.tomshardware.com/uk/features/crucial-p2-ssd-qlc-flash-swap-downgrade/2 (click the right triangle arrow and look at image 2). The 1000 Mbps they advertise is for the first 20GB so great for copying a few files but then it hits the floor.

Not saying that there aren't SSDs that are suitable as backup targets but that you have to be very careful to pick the right one. Tom's Hardware reviews almost always include the sustained write test.

Smallest NearLine Enterprise SATA drive which is probably 8TB right now.

A StarTech USB 3.1 external enclosure.

Put the drive in the enclosure.

Get several for a rotation.

BackBlaze for cloud backup as a secondary.

if not needed - i'd use a much smaller drive type, eg 2 TB or lower 

Thank you everyone. I realize I should have given more background. Excellent inputs and ideas as always.

This is for a user who prefers a simple setup. The external drive is just used for once-daily backups of about 20 GB user data. It is in addition to cloud-based backup via iDrive, again of mostly user data. I also occasionally do an image backup of the OS drive, which I usually store on the same local external backup drive we are discussing.

Based on your inputs I am thinking of two possible solutions:

SanDisk 1TB Extreme PRO Portable External SSD - either version 1 with up to 1050MB/s read speed or version 2 with up to 2000MB/s. The slower speed seems quite sufficient for the need.

Build my own: Samsung - 980 PRO 1TB PCIe Gen 4 x4 NVMe SSD in a Startech housing (either M2E1BMU31C or the rugged version M2E1BRU31C). I use some of these Samsung drives internally in another computer.

20GB won't even fill the 980 PRO's pseudo SLC buffer so you can ignore my performance warning for that one. Full backup will be to the back end TLC of course but that's still 1000MBPS if you can feed it that fast.

As was already mentioned, SSD's aren't really recommended for backing up, as they wear faster. I would just get a simple, commonly available, USB 3.0, 2.5" Disk. You could get several of them as they aren't expensive, at least for the low capacity you are thinking of. Then you can at least rotate between them, & if one breaks down, you have the other. With an SSD you probably also wouldn't get much faster speeds on a USB 3.0 system than you would with a conventional disk. Also with the backup sizes you are thinking of speed wouldn't matter that much either.

For that you don't have to worry much about quality or warranty. As I mentioned before, the warranty only covers the hardware, as the price for those is negligible, you don't lose much should the disk break (besides that you would possibly also have to pay for mailing the broken disk to the manufacturer). Warranty doesn't cover you for lost data. So there is no point in wasting too much money for a longer warranty period.

It is probably more important to look at how you are backing up, what software you are using etc. For Windoze OS's & file based backups, I'd recommend Cobian Backup, which is very easy to use & setup, and is also free, at least for private users, as far as I know:

https://cobiansoft.com

I concur that Cobian backup is a great software solution for personal / home backup on Windows, and in your scenario, you'd probably benefit from a simple enclosure with two small drives that you rotate, although I'm more inclined to use SSDs simply for more physical durability, even though they have less overall writes. The longevity of the write/reads on the SSDs shouldn't be a problem if you're doing incremental, once-a-day backups. In that case, they should last longer than an SSD in everyday use.

Cobian looks interesting although I just use xplorer2 (https://www.zabkat.com/), a superb replacement for Windows file explorer. It has a "backup newer, ignore others" capability that works well for this very simple once-daily backup.

I found the SanDisk Extreme Pro® Portable SSD 500GB drive (version 1) for sale directly from Western Digital / SanDisk for US$110 so I decided to go with that drive.

1400 Mbps sustained write for the 1TB version of the WD Black inside it, that's good.

I want to share my thinking as I close out this question. Many of you provided great insights and ideas that contributed to my ultimate solution. Seth Simmons suggested the same type solution as I used - external portable SSD with 1050 MB/s transfer rates - so while I used a different product - the SanDisk - I decided to declare Seth's response as a solution rather than say I found my own solution.

Ultimately if the user is amenable I will get a second external SSD to alternate between the two, in line with some of your suggestions.

Many thanks for helping me reach a decision.

Thanks, Pete