I can't pick one thats both but for Visual I'd go with the Francis Ford Coppola directed Dracula because its got these completely wild and imaginative fantasy visuals(the vial dripping upwards, dracula's shadow, the storm, the ride to the castle, etc) along with these gorgeous period visuals which are sometimes photographed at uneven film speeds and treated to look aged and other times just clean, deep focus photography of period scenery/clothing etc.
For sound I'd go with Eraserhead which is just constant, visceral and troubling. It's like durring the 70s there was this shift to very realistic takes on older styles like noir and ensemble films and this is like the only realistic and effective take on surrealist films. Like watching the protagonist experience a nightmare.