"least kind" is correct and can be used in written English.
For example, you could say: "He was the least kind out of all the people I interviewed for the job."
The person to whom he is least kind is Martha.
"Just giving visitors an open mike is the least kind thing you can do.
You are —I was, at least — kind of shocked when the waiter brings a menu and announces, "You can't really order anything, because we're bringing you everything".
Surface charm runs high in Marsha Norman's "Last Dance," a play that suggests that if loveliness is not next to godliness, it is at least kind of divine.
CBS would have to produce an almost amazingly bad melodrama for Hitler to come across as somehow sympathetic, or at least kind of cool -- sort of like Hannibal Lecter in "Silence of the Lambs".
At least kind of, sort of.
Although it is less comforting to believe in randomness, I take heart in the fact that it is at least kinder, more courageous, and true.
But that's not even the least-kind way we could describe Facebook's total decline from former heights.
And again... Keep the acorns of one tree (or at least one kind of oak tree) separate from other kinds.
Table 1 shows that 90% of welders were aware of at least one kind of PPE while only 47.7% of welders use at least one kind of PPE during work.
Most of them, 46/55 (84%), had a higher expression level under at least one kind of biotic stress, and 32/55 (58%) had a higher expression level under at least three kinds of biotic stresses (Figure 4).
