Originally Posted by Plankton

Although Kill Em All was a breakthrough album, I feel it lacked the production quality they had achieved with Ride The Lightning, and every album after (up to the point of And Justice, I won't go beyond that). Just a natural progression and evolution of available technologies. Also, they developed better as far as song structuring and took more chances melody wise with RtL. Kill Em All has quite a bit of your standard bar chord chug where there are more breaks, tempo changes, and melodic passages all through RtL. They kept this formula, and built upon it all through Master Of Puppets. And Justice was more of a "Back to the Drawing Board" album as they had lost Cliff, which was key to their creative process, but they did retain the same songwriting structure to which they had built upon.

So, based on that I have to go with Ride The Lightning.

...and why isn't Garage Days listed? Because it was an EP? It comes in at a close 2nd for me. Some great tunes on that one (although they were covers), and I can imagine them beating on Jason all while laughing their heavy metal asses off during recording.