which OS to install on a late 2013 21" iMac with 8GB RAM and HDD?

[beethovengirl]

A friend of mine, who is a light computer user, just "inherited" a 21.5" iMac 2.7GHz i5 / 8GB RAM / 5400 rpm HDD. It's currently running Yosemite, but she wants to install Microsoft Office 2019. MS says Office for Mac is supported on only the three most recent versions of macOS. Will Office 2019 install on an earlier OS? My impression is that High Sierra, Mojave, and Catalina won't run well on a late 2013 iMac without a SSD. Which Mac OS runs best on a late 2013 iMac with 8 GB RAM and no SSD?

[I have a late 2016 13" Touch Bar MacBook Pro 3.3GHz i7 / 16GB RAM / SSD, and I'm also wondering whether upgrading from Sierra will benefit me. I'm generally disinclined to upgrade unless absolutely necessary. I tend to have a zillion tabs open in Chrome, Safari, and Firefox at any given time, and I'm frustrated with how much this slows my MacBook down.]

thanks for any advice you may have

 

[barbu]

Catalina would be the best bet for future-proofing as it will remain updated and compatible longer into the future. You have correctly identified the weak spot in that system - the ancient HDD. However, this would be a bottleneck no matter which OS you choose. I always recommend staying up to date (updating should not lose your tabs, you can at least save them into temp bookmark folders if you are concerned) because you want to have the latest security patches, enhancements, etc.

 

[Fishrrman]

8gb of RAM should be fine.

I would NOT suggest Catalina right now. Too many folks having too many problems with it.
The Mojave OS might be a better bet.

BUT...
The platter-based 5400rpm drive just isn't going to cut it.
Your friend should consider getting a modestly-sized external USB3 SSD, plugging it in, and putting a copy of the OS onto that.
The computer will then boot and run MUCH faster.

I'd suggest something like a Samsung t5, 500gb.

Use Disk Utility to erase the drive to APFS, GUID partition format.

Then, download Mojave using this URL (takes you to the app store):

https://itunes.apple.com/us/app/macos-mojave/id1398502828?ls=1&mt=12

It will go to the applications folder.

Now, try running it (you didn't tell us WHICH VERSION of the OS is currently installed).
When the installer asks WHERE you want to install, point it at the external SSD.
The install may involve one or more reboots, and will take some time. BE PATIENT.

If successful, your friend will eventually see the setup screen (choose your language), and can proceed from there.

One other question:
Does you friend already have a Mac with data to be transferred to the new install?

 

[barbu]

I disagree that moving to an external USB device is a good idea. USB protocol has no hardware controller and relies on the CPU at all times to handle interrupts, etc, which is not ideal for the boot device. It is also much slower than the internal bus. Now I certainly would agree on, and advise, an SSD upgrade to the internal drive. That is a big job on the 2013 iMac as I believe it involves cutting thru the screen glue, etc., but it can be done (or have done). If that is too much, I'd stick with the spinner.

 

[Fishrrman]

"I disagree that moving to an external USB device is a good idea."

Nope.
I've been booting and running my 2012 Mac Mini from an SSD in a USB3/SATA dock from the moment I took it out of the box in January 2013.

It always ran great, and still does.

That's my experience.
Take it or leave it.

 

[barbu]

"I disagree that moving to an external USB device is a good idea."

Nope.
I've been booting and running my 2012 Mac Mini from an SSD in a USB3/SATA dock from the moment I took it out of the box in January 2013.

It always ran great, and still does.

That's my experience.
Take it or leave it.

sure, that's fine, you do you. My concerns with that arrangement remain. Have you ever benchmarked the IO and compare it to an internal HDD? I am genuinely curious.
If OP wants to go external, I would seriously push them in the Thunderbolt direction. That bus is much faster and has a proper dedicated controller.

 

[eric89074]

I recommend replacing the internal HD with an SSD. I'm not that experienced with computer repair and I did it pretty easily on a 2013 21.5 imac. You can get the replacement adhesive strips for $7-$8 off amazon with the pizza cutter to remove the old adhesive. I took my time and did it in a little under and hour. There are a few guides on youtube you can follow along with too.