I love the sound of Maggy snoring. It's so cute to hear that little girl make so much noise!

I love Sammy and Payton's purring,
My hubby's laugh
My mom's voice (dad's too, though I'll never hear it again)
Mariachi music
Maggy's little nails on the tile floor (grandma calls her pitter patter)
Maggy's juicy kissing noise

Many more, but those are the first that came to mind.