All of the portable ones can't give you 40Gbps because they are passively cooled and use a low power chipset so that it can be bus powered. The Sabrent enclosure can do about 10GBps, and the OWC Envoy Express can do 12Gbps. There's one made by Trebleet that looks like it might be able to do ~21Gbps, but without active cooling, your drive might not last as long, as the enclosure will get burning hot to the touch, and the slick/smoothness of the enclosure is not as efficient in heat dissipation.
The Sabrent one also comes with a proprietary cable end (there's a nub in the recessed port that fits into a notch on the cable so that you can't just use any cable)
The OWC Envoy Express uses a genuine Intel Alpine Ridge chip, but people have been reporting issues with some SSDs, and there's two versions (the initial batch and then the revision), and it's not known at this time whether the revision has fixed anything. The upsisde to this enclosure is that the cable is replaceable.