Neither. The red one. (Off) is the most extended.
Why do like them more? What is there to like?
I'm not sure that
@eyes-on-you is talking about this extension. I've already saw enough examples where some people talk about extended frequency range (so what you're answering to), but also some talking about the longest extension
of the flat response, but only in the audible range.
Now, like you said, if you want to avoid hardware problem, better avoid risking a filter that extend higher than the audible range. The only point where I don't fully agree is the "best case, it just does nothing" because it's right from the same "hardware" point of view, but from what you hear (and depending on the content of what you're listening), the filter has not a impact in frequency response, but also in the time domain, and it's not only a measurement of impulse response that is different, you can hear it difference between some filters
I tested it on a DAC, and could ABX between some filters (not between all), and after finding the one I prefered and the worst in my taste, I measured the same recording done with each filter, and guess what, one I like was not the "perfect filter", but once comparing to the original track with DeltaWave, it was one of the two best results with less difference with the original than with 5 other filters, including one looking more like a "perfect filter"
So the filter question might be more complicated than what we thought or how we are used to describe it
