SL-20 hands down without a doubt. I had Maglites, and my partner had a Maglite rechargable. His was a little brighter than my battery one. However, we both just got SL-20 LED's about a month ago, and it's like night and day difference! Doing building searches is where you really appreciate the difference between them. The Maglites have dark rings and spots in the beam, and the Streamlight is a very nice clean beam. It is also brighter than the Maglite.
The best place I found to get them was Botach Tactical.