One thing I love about zdoom is how easily you can change almost anything around in it. I also love, due to those capabilities, how people have taken the time to make their own personal enhancements to the game. Stuff like Beautiful Doom, Doom Enhanced, and countless others go the distance to make the Doom experience even better.
So that leave's the question: What's your favorite Doom enhancement wad? Or how about something more specific like, what's your favorite aspects/features about an enhancement wad?
To start off, here's my recently finished Doom enhancement wad simply title Doom Expanded (expanded.wad, yes shameless plug.

). This contains elements of the aforementioned enhancement wads (Beau. Doom, Enhanced) as well as the smooth weapons mod and the high-res sound mod. The only thing I officially claim as my own is the Smooth animation for the BFG 9000 which you can learn all about the making off right here:
http://forum.zdoom.org/viewtopic.php?f=3&t=28543
Here's my Expanded wad off Media Fire:
http://www.mediafire.com/?h4mdwdt9q5czcqo