My recommendations for the top five actors nobody uses as soundboards:
1. Nicolas Cage - the king of Hollywood insanity. Best movies for audio would be Matchstick Men, Face/Off, Leaving Las Vegas, and Adaptation.
2. Billy Bob Thornton - not just Karl Childers which people do. Recommend getting audio from Bad Santa, The Man Who Wasn't There, Bad Santa, Bandits, A Simple Plan, and did I mention Bad Santa. "I beat the shit out of some kids today. But it was for a purpose."
3. Clint Eastwood - huge library of films to choose from and as iconic an actor as Jack. My recommendations would be Gran Torino, Dirty Harry, The Outlaw Josey Wales, and The Good, The Bad and The Ugly.
4. John Malkovich - another actor ripe for a soundboard. Best movies to use would be In The Line of Fire, Burn After Reading, Con Air, and of course Being John Malkovich. "MALKOVICH!"
5. Bruce Dern - obscure compared to the others I know but he wouldn't be quickly recognized and has a load of insane quotes. Best movies to use would be The Cowboys, Silent Running, The King of Marvin Gardens, and Posse.
Runner up: John Goodman.
I posted this almost a year ago. Haha.