For the sheer gruesomeness I have to pick Phil Leotardo's hit. Even though they don't show it you can just imagine the truck tire slowly rolling over his head until it pops send brains and blood flying all over the service station like some Sicilian piñata.
The best hit as far as good TV goes has got to be Bobby Baccala. One minute he's buying a train then BAM! He's causing a bigger wreck than Amtrak. What puts this over the top for me is the way the miniature people on the train set react to the shooting. Great idea!