External hard drive?

What is the best external hard drive to buy to connect to a late 2013 iMac 3.2ghz with 8g memory? Any high quality brands? Size? I had a Western Digital but it broke.

Honestly, "best" is highly subjective. There are far too many variables for anyone to offer much more than an opinion based upon their own personal experience and needs -- and the specific computer you have is just one more of those variables. That said...

You mentioned a 2013 iMac, which means that you have the older Thunderbolt ports with a Mini-DisplayPort interface (instead of USB-C), alongside some USB3 ports. If "best" to you means "fastest", than you might want to take advantage of those Thunderbolt ports -- but if memory serves, those older Thunderbolt devices tended to be expensive. On the other hand, if "best" to you means either "most cost effective" or "most future proofed" than maybe you'd be better off eschewing those legacy Thunderbolt ports and instead getting a more modern USB-C drive with a USB-3 cable. (Most USB-C drives come with a USB3 cable in the box, along with a straight thru USB-C cable.) Both are perfectly valid options, depending upon your use case.

Another variable is the technology of the drive itself: HDD vs SSD. These days I tend to err on the side of recommending SSD pretty much every time, as they tend to have a much longer life than a spinning-platter-drive, particularly in anything portable. (HDDs really don't like it when you move them around.)

Personally, I purchased a PNY Pro Elite 1TB to backup photos from a 2012 iMac, and have been quite satisfied.

This would all depend on how much storage you need and how fast you want it to be.

You can get much larger HDs than SSDs, but the tradeoff is speed with the SSDs way outperforming the HDs, and price, the HDs being much cheaper. The Thunderbolt ports on this iMac can do 10 Gbps whereas the USB 3 ports have a max of 5 Gbps. USB in newer versions of macOS is also susceptible to the "unexpected disconnect" problem whereas Thunderbolt is much more stable.

For hard drives I've had very good luck with the WD Gold Enterprise Class HDs. For SSDs I go with Samsung Pros. Both are on the pricier end of the spectrum.

What kind of budget do you have for this?

zarmanto said:

Honestly, "best" is highly subjective. There are far too many variables for anyone to offer much more than an opinion based upon their own personal experience and needs

There are 3 parts to an external drive: the cable, enclosure, and hard disk. There is extensive objective data on hard drive life available from Backblaze. The other 2 items require research.

zarmanto said:

These days I tend to err on the side of recommending SSD pretty much every time, as they tend to have a much longer life than a spinning-platter-drive, particularly in anything portable. (HDDs really don't like it when you move them around.)

SSD's are certainly recommended when portability, poor environmental conditions, etc. are involved. As far as longer life they do not necessarily last longer. Some good HDS can have a 10x longer life than an inexpensive SSD depending on usage. I always recommend HD's due to their lower cost and higher capacity. Backblaze data on SSDs is not sufficient to do an objective comparison, but should be available in a few years.