best external drive option (product recommendation)

The speeds you WANT and the speeds you can get are two different things.

A USB-C connection provides a 10 G bits/sec pathway, not 40. That's a theoretical 1,000 M Bytes/second, but real-world results will be lower.

The only way to get higher maximum TRANSFER speeds is by using Thunderbolt. Practically speaking, that can provide around 2500 M Bytes/sec top speeds.

There are no drives with DIRECT ThunderBolt interfaces, so you WILL be using a ThunderBolt enclosure, you just have to decide how many bays of what type, one or multiple, NVMe or SATA or something else.

Mechanical drives:

The best mechanical rotating magnetic drives can supply a burst of data off the platters at around 150 M Bytes/sec. Then there is dead time while it seeks. That is not slowed down very much by USB-2 interfaces, and not at all by USB-3

there is a big speed void in between.

How fast does your wallet want to go?

<< USB4 protocol can provide up to 40Gbps through a USB-C port. >>

yes it CAN, PROVIDED you connect a genuine USB-4 external enclosure and use an appropriate cable.

¿Want to see a cute trick?

On the OWC/MacSales web site showing ALL external drives, just check the checkbox in the sidebar to display ONLY USB-4 devices!

The list goes BLANK.