The Knog Blinder series has a very nearly completely uniform lighting pattern across about 120 degrees, and is visible to 180 degrees. I don't think it's possible for any light to be any more wide and uniform.

Here's a video of a garage door test that includes the Knog, see especially at the end in flash modes.
Bicycle taillight comparison - reflective - YouTube

Here's another video that shows what they look like direct rather than reflected.

Taillight test 2013-04-09 - YouTube

As you can see, the knog is extremely uniform across the entire width, but the straight on tests show that a couple of the others totally swamp it for light output. Even though it drops off a lot, the Serfas TL60 is so bright that at an angle where it's dropped off it's still probably brighter than the Knog with its uniform distribution.