If you're talking about an IR producer in Japan (
https://dynax-japan.com/dynax-ir/), it's liked among Japanese guitarists mostly due to the native Japanese support (as most of the famous IR producers are from outside of Japan) and probably the sound character suitable in J-Pop context.
I once tried the free samples but it was not my liking, however. Maybe it could be just me but I remember the attack of the notes/chords became unnatural, somewhat "flat" when their IRs were loaded. I checked out the waveform and turned out they made it as "Minimum Phase IRs" as the default (see Fig.1). Also, the "tail" of the Dynax IRs had unusual signal level for an IR (Fig. 2). While it was not an audible noise, it could suggest there's some postproduction, probably dynamic range compression, that has been applied to Dynax IRs.
Maybe Dynax could be good on its own, but If you want more natural sounding IRs, I don't think they're better choice over other existing, already renowned producers.
The following screenshots are the comparison of waveform vs York Audio IRs: Top - DYNAX, Center - York Audio minimum phase, Bottom - York Audio non-minimum phase:
Fig.1 First several samples:
Fig.2 Entire IR:
