Thanks for reading and for the question!
And hah, I don’t blame you for asking me this one either, since it’s one I’ve gone back and forth on over a few of my different articles. But that should give you a big hint: It’s really close and largely up to personal taste.
They’re all what I would call “good,” so it just depends on the sort of signature that you like, and what you’re in the mood for.
I think the 100AAP has the most relatively balanced sound of the group. It’s sculpted just enough to be exciting for consumers.
The M50X is a little more punchy and aggressive in certain areas that help with sound mixing/monitoring. Those emphasized areas are what make it a love-it or hate-it headphone. The 1A is more of a warm, smooth, relaxing Bose-style sound.
So if you like a reasonably neutral sound with just a touch of sculpting, the 100AAP is a good pick. They’re pretty darn good at detail retrieval for the price.
The 1A has a much more luxurious, deep bass to it. If you’re a big fan of bass and sub-bass, you will prefer the 1A. These frequencies aren’t lost on the 100AAP, they’re just rendered better on the 1A. They both have comparable soundstage, and neither isolates as well as the M50X.
It’s tough, right? You might just have to listen to them for yourself and decide, and make sure you buy from a place with a good return policy!
As far as comfort goes, I’d rank them 1A > 100AAP >M50X. The 1A is one of the comfiest headphones ever made, and the 100AAP is only a notch below that. The M50X is a bit clampy by design, since it was designed for production environments.