First I will go over the setup for those who are interested:
I took slow motion video with my iPhone at 240fps with the controller in the foreground and the TV in the background while in the "test buttons" section within the Switch's settings. Counted the number of frames in the video between full button press and the first sign of the screen reflecting the input. Although I didn't use an active light indicating a button press (like Shmup Junkie’s video comparison), the controller being in the foreground made it very easy to tell which frame of the 240fps video the button was activated so I am confident in the results. The TV model is LG 55SM9000PUA which has been measured by rtings.com to have a 13.8ms response time at 1080p 60Hz - https://www.rtings.com/tv/reviews/lg/sm9000
The Mayflash Magic NS has 2 different selectable modes for the Switch: One is the "Nintendo Switch System Mode" which is identified when the adapter is flashing red, and the other is the "Switch Pro Mode" which is identified when the adapter is flashing purple. The only difference between the two that I noticed is that the "Switch Pro Mode" (Purple) enables you to remap the controls within the Switch's settings, as I assume the system thinks you are using an actual Pro controller which enables this option (The Wingman NS enables this option within the Switch's settings as well). I never experienced a noticeable difference in response time so this has been the mode I have personally used the most. However I measured both modes just in case.
After 50 measurements each between the Magic NS (Purple), Magic NS (Red), and the Wingman NS, here are the results:
Magic NS (Purple) - 5.56 average frames at 60Hz
Magic NS (Red) - 5.27 average frames at 60Hz
Wingman NS - 5.35 average frames at 60Hz
For a reference comparison, an actual Nintendo Pro controller (wireless) measured an average of 4.77 frames at 60 Hz.
Here is a table showing the breakout of the number of occurrences by frame #:
Surprisingly, the Mayflash Magic NS’s “Purple” mode averages about a quarter frame of input lag higher than the “Red” mode, and it was pretty evident as the lowest measurement for Purple was 20 frames (240fps) which only happened 3 out of the 50 measurements, where the Magic NS “Red” mode had a lowest measurement of 19 frames which happened 6 times out of the 50 measurements.
The Brook Wingman NS averaged about the same as the Magic NS “Red” Mode, although it did have 2 measurements at 18 frames (240fps) it had a lot more measurements of 23 frames to offset it.
So if you have the Magic NS adapter and you don’t care for the ability to remap controls in the Switch’s settings then I would recommend using the “Red” mode. If whatever you are playing allows you to change controls in-game then it doesn't matter anyway.
* An additional note: After some quick comparisons between the "Test Buttons" section and some actual gameplay I found out that the test button screen is a little slower than the first sign of ship movement in Rolling Gunner (around 0.75 to 1.00 60Hz frames, or 3 to 4 frames of 240fps video). Although the test buttons screen is not the best representation of "most optimal" timings, it is very consistent and much easier to get a larger sample size of measurements so it served my purpose of comparing adapters quite well.
As far which adapter is better overall between the Magic NS and the Wingman NS, it’s really a matter of which features mean more to you:
Magic NS - Can switch A-B to B-A and X-Y to Y-X if you don’t like Nintendo’s button layout. You can adjust vibration intensity, and adjust the analog stick deadzones (which is huge for me as my XB360 controller sticks are very loose).
Wingman NS - Has a turbo function and the ability to remap controls. For example, you can remap X as “A+B”. There is no deadzone adjustment, but it is more forgiving than the default settings on the Magic NS, just not as forgiving as the Magic NS’s max deadzone setting.
So there you go, all of that time spent to identify a quarter frame difference . On a serious note this was pretty fun to do though… Now that I found a decent system for measuring input timings, I also have a Retro-Bit Saturn Controller (Bluetooth), the 8Bitdo N30 Arcade stick, and a Pokken Tournament wired controller that I would like to test in the future as well. I have no idea of when I will be able to get to them though.