So according to what they write in those reviews Mach Xtreme LX is MLC and Samsung MUF is TLC(and it's nowhere stated that it's 3D TLC, hence probably not). I've found some CrystalDiskMark screenshots and it seems that in sequential writes Mach Xtreme LX is twice as fast but in random 4K writes it's tanking badly behind Samsung MUF. Would such values matter in real life daily use?
That kind of depends on the type of use they will see (which in turn depends on you) so that is a bit difficult to say.
As of note, some people do report that when there's much of smaller files to be copied over USB 3.0 many cheaper flash sticks get really warm and could overheat. When it happens they will either tank copying speeds to really low values for brief periods of time(better ones) or completely shut down themselves for few second(worst case) effectively interrupting transfer. And such heat could be damaging not only to drive itself but also to USB port. Really don't want to end in this area and it's said even some med-range SanDisk drives could be affected.
It's not just with a lot of smaller files.
Just some sequential writes can make several compact USB-drives to get really hot and disconnect.
In that regard, I've found the Samsung MUF FIT to be pretty good - it still gets pretty hot but not as hot as some other drives.
And even more importantly that they maintain pretty stable write speeds and do not disconnect every now and then (don't remember that happening with a Samsung MUF FIT actually).
Sequential write speeds may be a bit low however at around 30-40MB/s (for the 128GB).
Picture of the drive in question so that you know which drive I'm talking about.