External boot drive recommendation

I have a 2017 27" iMac. The internal fusion drive (HDD portion) is failing. I’d like to run this computer for a couple more years. I don’t want to invest in replacing the internal drive since I don’t think I’d get that back in resale. This leaves booting from an external SSD. I’m looking for recommendations for a 2TB SSD that I can use as an external boot drive. My assumption is a drive with a USB C/Thunderbolt 3 connection will give better performance. Thanks in advance for any suggestions!

I used a 1TB Samsung T-5 with a 2018 Mac mini until the Mac died. I could tell no difference in speed between it and the 128GB internal ssd that it replaced. I now use the T-5 with my iPad Pro.

Samsung offers a 2TB T-5.

After trying two other drives, I recommend buying the OWC Envoy Express and whatever NVMe SSD you find on sale (but do check the fine print on OWC’s website - there are two models that are incompatible).

I’m using it as the boot drive on my 2019 5k iMac, and Black Magic Disk Speed Test shows 1300MB/s writes and 1480MB/s read speeds.

It is faster and more reliable than the Samsung and SanDIsk USB-C portable drives own.

My 2017 runs very well with a 1TB T5 too.

I have a 2011 iMac that runs fine with a replacement internal SSD from 2015. I think I paid $500 to replace the internal drive and replace the optical drive with a 2 TB HD. $85 / year or so has been well worth it.

Thanks everyone! The T5 was on my shortlist, so I decided to go with that based on your recommendations. I know an NVMe SSD drive would be faster, but availability and price aren’t great in my country. The T5 is cheaper and easier for me to purchase. And I’m coming from a fusion drive, so the T5 will feel plenty fast! I’ll put the savings in the piggy bank in anticipation of a new Apple silicon machine in a year or two.