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.
My particular testing was with an SSK SD300, which is roughly 500MB/s up and down. I have benchmarked this and confirmed it meets its rating.
I have thought about buying something like a Team Group C212 or Team Group Spark LED, which are rated at 1000MB/s. The 256GB version of the C212 is available on places like Newegg and Amazon for around $27 USD at time of writing, but they make variants as high as 1TB.