Davros, I found the lyrics of your favorite song in the 1966 song book. It is song 105 and is called "This Is Jehovah's Day!" In reading the words of that song I now think it was my favorite JW song and that the "We Are Jehovah's Witnesses" song was my second favorite JW song, or perhaps tied with it. Song 105 (195 in 1984 song book) is one in which I memorized much of the lyrics while I was a JW.
I also liked the lyrics of the chorus of songs 11, 13 (33 in 1984 song book), 59 (112 in 1984 song book), and 76 (143 in 1984 song book) of the 1966 song book.