Originally Posted by zippy100012
another level i like has got to be E3M9 Dis. same beginning of E3M1 right up to the end as you think it is.
I think you're thinking of Warrens. Dis is the final boss level.
As for my favorite levels, I always liked E2M6, the Halls of the Damned in Doom 1. I like how the exit is near the beginning, but you need all 3 keys to get to it. The evil music is also a very nice touch, and let's not forget the fake exit!
In Doom 2, I always liked Level 23, Barrels Of Fun. The level's name describes it perfectly, all set to a MIDI rendition of Alice In Chains' "Them Bones."
In Final Doom, I haven't really played TNT Evilution all that much, but I played the hell out of The Plutonia Experiment. Some of my favorite levels from that WAD are Level 6: Baron's Lair, Level 15: The Twilight, Level 24: The Final Frontier, and the two secret levels. I like how they made the secret levels the hardest in the game.