Yeah, this is a tough one, but Caught in a Mosh is a big one for me. It was the song that really got me into Anthrax, mixing a sense of humor with a killer riff.
Imitation Of Life.... Anthrax has always had cool songs to end albums, and this is probably one of my fav's. The whole album is pretty good, and Caught in a Mosh is a prety close second.