The stock maps from Nexuiz are in DESPERATE NEED of being included with Xonotic in my opinion. The game still doesn't feel entirely like it's successor without them and when I say they need to be brought back, I mean they need to be brought back AND still have the same spirit they previously had in terms of art direction, gameplay, and overall atmosphere. Anyway with that said, these are the ones I'd most like to see come back:
Reslimed (Easily one of my favorites for deathmatch.)
Downer (It was remade, but didn't come close to capturing what made the original great.)
Aggressor (It was retextured once or twice, but didn't have the same feel that it did in Nexuiz 2.4.2 and earlier.)
Skyway
Bleach (Got an awesome remake by Cortez that I love as much as the original, but still isn't part of the game. It needs to make it in the game.)
Strength (Screw remaking it, just import it into the game and call it a day.)
Desert Factory (Same deal as Strength, though the textures used in it could use an upgrade.)
Aneurysm
ECKZBAWKZ HUGE LIST OF ACHIEVEMENTS GOES HERE....
Oh wait.