What is your favorite (individual) level...

1. in the original Wolf3D/SoD games?
2. ever made (either original or custom mapset/mod)?

Mine:
1. Ep 6 Level 8 Wolf3D
2. ATAW3D Level 69

E6L7 and a tie between Totengraeber's level 13 and Schabbs 2000's level 41.

Well all three of those levels take on a mazey layout, but IMO they aren't mazey in the way that really gets on my nerves, primarily because they very much have other aspects to them than just a maze, or in the case of E6L7 a lot of the maze exploration is optional. I kind of see the style you're going towards, as both Totengraeber's Level 13 and Schabbs 2000's Level 41 are generally a network of hallways with plenty of doors, some smaller corridors, and a few bigger rooms all laden with mutants, i.e. the two levels bear some similarities (even though they are different colors and by different authors).

I also have a soft spot for Spear Resurrection's level 13. It's so great when you have to start all over again in the middle of the game. It freshens up the gameplay, and makes you want to explore in the same curious and cautious fashion you did when you started that game. I spent a long time in that level getting the full hundred, I tell you that!

I agree with you there Thomas. It's the first mod I played that you lose your weapons halfway into the game. Very clever idea back then, and it still is now.