I know it's more of a cheer, but I love Pi Pi ADPi...it always gets stuck in my head and then I sing it all the time. I also love Grandma was an ADPi (since I FINALLY learned it!) and I Love the Pin.
I also love our rose ceremony song (candle pass more recently). I always want to sing it again and again, because the times between use for the song can stretch out, and you tend to forget the words! We always sang the blessing when we got together (with food), so that's also a personal fave!