Come on, now, not "oh, I love them all"... what's the one you always grab for in a pinch?
Mine is the background splatter stamp by Raindrops on Roses. It's much like your typical splatter stamp, but with a sprinkle of stars in the mix. The stars make it for me. Whenever a card is "missing something", a spritz of that background usually does the trick (that, or glitter glue!)
Alison