My favorite map would be: Purple Dimension
The Link:
http://ugx-mods.com/forum/?topic=5078.0Why is it my Favorite: I had a lot of fun playing this much, the detail was incredible, the map maker clearly took a lot of time with these detail which really make the map stand out, the wide range of weapons in the game is just amazing. the maze was trippy as hell. an a 85K ending, also has buildable and a quest you can do... i had a lot of fun playing this map with friends