I agree with Niels that "You are what you is" is the best collection of songs he ever did. Allthou "Joe's Garage" comes close!
I saw allumi George Duke live in Tivoli-Copenhagen this summer and he played a medley of Zappa songs in the ending of the concert at a tribute to Frank and all the concerts they played together in Copenhagen i the 70's when George was a sort of "Concertmaster" i Zappas band. Nice to her those melodies again. There is not many who can/will do those songs, these days.