As what amjith said -- however, I personally find myself working with upwards of 3+ different databases in a single day. I may not be the use case, but eventually I realized it would have been easier to write a single, consistent client that works across all databases the same, as opposed to learning yet another broken, random client.

Since usql is written in Go, it compiles to a single static executable, and as such you don't need any extra dependencies. {pg,my,db}cli requires pip + python, which is usually broken on many systems that I've been an admin on. Also, good luck getting pip working properly on Windows. Also, since its written in Go, its likely significantly faster.