It's very close between the Silly Song and the Washing Song, but the Washing Song takes it if only cuz Grumpy gets dumped in the water. Awesome!
I guess I'd agree with most of this, though I thought the Whistle While You Work song was a bit better than Silly Song. I also forgot to mention in my review that the music, while good, consisted of songs that were far too short and underdeveloped, with the definite exception of Whistle While You Work and the Washing Song, and half of Silly Song, you know the parts where they actually sang stuff.
EDIT: Also, why is Heigh-Ho winning by so much, did you people watch the film? Sure it's iconic, but they literally just repeat the same thing and whistle, there is no sort of lyrical depth or developed ideas going on in that song, just whistling and like two sentences.