"Drow" to rhyme with "cow," NOT "Drow" to rhyme with "row" (as in rowing a boat, or aligning things along a line). This is according to Gary Gygax, in many, MANY GenCon speeches and seminars, not me. ;}

— Ed Greenwood (@TheEdVerse) June 21, 2020

And being as Gary put the drow into the game (no, he didn't invent them, but he invented the version of them seen in D&D), I bow to his preferences.
In the Realms, with regional accents, you'll hear both pronunciations. ;}

— Ed Greenwood (@TheEdVerse) June 21, 2020