The Terminator (even though B & B is the better movie, IMO) Stand By Me E.T. The Extra-Terrestrial (6th Sense is the better movie, but E.T. is already a classic) neither
It's absolutely criminal to put two films that are both undeniable 'future classics' against each other this early. But I'm going to have to go with Toy Story, first computer animated film establishes it, for sure. The Untouchables Toy Story Batman
A Fish Called Wanda vs. Ran - Two stinkers. Neither. The Fugitive vs. Rain Man - Two great ones. Rain Man is probably more apt to be a "classic" though.