Stan Lee, Jack Kirby, the Fantastic Four and the first appearance of the Silver Surfer--nuff said.
Arguably the best issue of the Fantastic Four. This issue introduced the Surfer, one of the coolest dudes EVER. Stan Lee and Jack Kirby were at the top of their form when these issues were being produced. They're an interesting look at the pop culture of the 60s as well. I highly recommend this.