Hmm . . .
1. Noir
2. El Cazador
3. Madlax
Noir's the unquestionable champion of them all, it has such an aura of mystery and breathtaking atmosphere, it is mesmerizing and does not let you go. It is leisurely paced like all non-Murder Princess Bee Train anime, but the quality storytelling and superb characterizations suck you in.
El Cazador's fun personality gives it an edge over Madlax, which I found to be too much of a Noir-reprise and took leisurely pacing to an all-new level, Madlax actually put me to sleep more than once. Madlax lacks the atmosphere and suspense of Noir, and eventually frustration sets in because the story takes FOREVER to go anywhere. I finished it but I have never gained the urge to watch it again.
But El Cazador is a worthy show in its own right. It's just fun to watch, and is more exciting than Madlax is too. It's a different beast than Madlax or Noir but that doesn't make it a bad show, just different.