I use Beethoven's Fifth Symphony (conducted by Carlos Kleiber with the Vienna Philharmonic) as my benchmark. ?
Same piece but Gardiner’s Orchestre Révolutionnaire et Romantique is my favored recording. I'm noticing that the low-mids of the Airpods Pro are a bit too emphasized to my ears, giving a "boxy" sound, which is most noticeable with pieces that have a lot of tympani. The 4th movement is a good example... what I would describe as the upper portion of the tympani's sound (the more percussive initial attack that doesn't have as much of a readily distinguishable note to it, as opposed to the lower harmonics that ring out afterward) is too pronounced and tends to overpower.
In contrast, the Sony WH-1000MX3 sounds noticeably better in this regard. But I'm also aware that the APP might very well be more "right" than the Sonys and that I'm simply more used to the latter's sound profile, so perhaps I need to give myself more time to get used to the APP.
What's a shame is that with a little EQ dialed in (on my Mac), about a 3db cut in the 250-500 range, it's much more pleasing (maybe not exactly like what the Sonys sound like, but good enough to where I'd have the Sonys packed up for return right now). But I don't have that option on the iPhone. The "Classical" EQ preset is good enough, but it only works with the iOS Music app (I use Primephonic).
Anyway, I'll give it a few days before deciding which one I keep.