The deathstalker and its relatives, and the most medically significant scorpion genus in the hobby by a clear margin. L. quinquestriatus venom is among the most potent measured in any scorpion.
Everything else is secondary. Yes they are attractive, yellow and slender and fast. Yes the husbandry is straightforward arid setup. None of that is the operative fact. A serious envenomation is a hospital admission and antivenom availability outside the native range is not something to assume.
They breed in captivity and are not expensive, which produces the same dangerous mismatch as Stromatopelma: the price communicates nothing about the risk. Anyone keeping this genus should be doing so deliberately, with a plan, and not because it was affordable.