I'm pleased with the value for money.
I have the 64 and 128GB sticks. When I bought the 128GB size, I found it odd how the 32GB version was 2 euros more than the 64GB one.
I used two interfaces for the benchmarking: 3.0 and 3.1. 128GB reads at ~396 and writes at 65-ish on both interfaces. The 64GB version has the same read speed but its write is almost half at 35 MB/s. Based on this, I would pick the 128GB one.
For reference.
USB 3.0 (2008) - 5Gbit/s (Gen 1)
USB 3.1 (2013) - 10Gbit/s (Gen 2)
USB 3.2 (2017) - 20Gbit/s (Gen 2x2)
From Wikipedia: https://en.wikipedia.org/wiki/USB#Connector_type_quick_reference
This stick is indeed USB 3.1, so it should be twice as fast as a reputable USB 3.0 stick. The above speeds are theoretical (always) and shouldn't be used for comparison. In practice, overhead in data transmission, protocol conversion, error correction, and other processes reduces the actual speed. This results from multiple small files taking longer to transfer than one big file. Advertised speed doesn't consider real-world complexities.
I did expect a significant difference across the two interfaces. The USB 3.1 one is a PCIe card that came with my mobo (Asus rampage v ext. for those wondering). Maybe the card's old, who knows?