I am planning to get an external storage for Ventoy use. My current random usb 3.1 stick writes .iso-files with only 10-15 mbps only. I found this webpage for usb stick speed comparison: https://ssd-tester.de/usb_stick_test.php
The fastest usb sticks writes 800-1000 mbps in the crystaldisk-test.
If you have personal experience on this, please recommend which approach is better.
A USB stick will be fine for ventoy unless you are using persistence and writing lots of data to it.
An NVMe drive in an enclosure is better if you don’t mind the larger size and higher cost. A good NVMe drive will contain higher quality flash memory and have better wear leveling than a USB stick. There are USB 4 and thunderbolt enclosures available that can transfer over 3 GB/s.
Reminder to check the chipsets on your enclosures. Return anything made with JMicron, they’re crap and will overheat under long transfers.
Possible typo? I think you meant to wright “aren’t” in the first sentence.