Best external hard drive for mac.

What would be "best" would be an external drive that meets all of your expected goals for its use and your budget limit ... so, if you can answer some additional questions, we may be able to point you to some drive options that may work best for you.

They are;

• What is your primary goal for this drive? That is, do you want to use it solely for backups or for file storage. Note that you shouldn't use a single drive for both.
• Is data transfer speed performance critical to you?
• If you intend to use this drive strictly for Time Machine, how large is your iMac's internal storage? Will this be the only Mac you will be backing up?
• What version of macOS is your iMac currently running?
• Your iMac has four USB-A & 2 USB-C (Thunderbolt 3) ports. The latter provide greater data transfer rates. You then have the choice of getting an external drive that can support either. Note that those that support Thunderbolt will be more expensive.
• Finally, what is your absolute price cap for this drive?

Since your WD My Book is five years old, it should still be reliable and can be used as a second external drive for your Mac.

For Time Machine (iMac), I use a SAMSUNG T7 Portable SSD, 1TB External Solid State Drive. I bought it in June of 2022. I use it with my current iMac (2023) and used it with my old iMac (late 2013), as well.

I forgot how much I paid for it, but it currently costs around $90 on Amazon.

I'm happy with it.

At some point, I will probably be proactive and replace it as I've had issues with previous HDs (used as a destination for Time Machine backups).