I would say they're pretty close in brightness but in very different way. With tightest focus on both lights, Surge has a smooth bright hot spot; Stinger has brighter, smaller and sharper hot spot.
For general use, I prefer Surge due to its smoother beam. Stinger prevails in carriability. Not that Surge is bad in durability, Stinger (even PolyStinger) is simply tougher.
However, both of Surge and Stinger are far from US.
Alan