Pretty hard to choose, but E1M7 is always my favorite level to play when re-playing Doom 1. E4M1 is also a good choice. Refueling Base is one of my favorites from Doom 2, and No Rest For The Wicked is fantastic from beginning to end.
https://www.youtube.com/watch?v=3bKG0p6Tv9Q
This was actually recorded in 1965, for the film "Beloved Invaders". Nontheless, still an amazing performance from one of my favorite bands.