I'm not aware of a head-to-head comparison. My impression is that they have slightly different aims. PRQL intends to express analytical queries as a series of

I'm not aware of a head-to-head comparison. My impression is that they have slightly different aims. PRQL intends to express analytical queries as a series of transformations which form a data pipeline. My sense is that Malloy aims more to provide a kind of semantic layer as well as dealing with nested data and reports. (Disclaimer: I'm a PRQL contributor.)