What’s the BEST external SSD drive to backup my iMac?

Welcome!

An SSD is extreme overkill as a backup drive. A quality 3.5-inch drive inside a USB3 enclosure with an independent power supply is plenty fast once the first Time Machine backup is complete. They are also far cheaper that any 4TB SSD.

I gave up on "name-brand" external drives long ago . The drives inside were OK but the enclosure quality was not. They seemed designed to go on sale every other weekend, not for long and reliable service.

We use these exclusively on two iMacs and two MacBook Pros and have never had an issue:

https://eshop.macsales.com/item/OWC/ME3NH7T04/

Compare to the price of a 4TB bare SSD that still needs an enclosure (Yikes!):

https://eshop.macsales.com/item/OWC/S4D7E6GT4.0/

AVOID all "bus-powered"† drives that hold 2.5-inch laptop drives. A desktop computer does not need a mobile external drive. Neither does your valuable data.

† — "Bus-powered" means the drive has no power supply and has to get all its power from a USB port on the computer. They are the least reliable option.

Hi jhollan1,

Welcome to Apple Support Communities.

For Time Machine, an SSD isn't required. Take a look at the LaCie 6TB d2 Professional Desktop Hard Drive - Apple Store.

For a clone backup, i.e. CCC, an SSD is very nice. However, you cannot find a reasonably priced 4TB+ SSD. For this, take a look at this 2TB SSD: LaCie 2TB Mobile SSD High‑Performance External SSD USB-C USB 3.0 - Apple Store. It also comes in 500GB and 1TB.

-Jack

What kind of backups?

You really do not need a fast SSD to backup with Time Machine. Something like the reliable OWC Mercury Elite Pro will do just fine for your Time Machine backups.

see > https://eshop.macsales.com/shop/owc-mercury-elite-pro

If you want to make bootable clone backups in addition to Time Machine, then a faster external SSD could be worth the extra expense.

for the OWC line-up see > https://eshop.macsales.com/shop/external-storage#drive-configuration:single-bay

Personally I run Time Machine on a spinning external HDD that is 3 times larger that my internal drive.

Plus I make and update a bootable backup clone on an external SSD using CarbonCopyCloner.

see > https://bombich.com

Can recommend the Toshibas - great value for the price + 3 year guarantee.

https://storage.toshiba.com/consumer-hdd/external