Count me in as someone who's gone back to the Momentum 3 from the Shure Aonic 50. Mainly due to the more dynamic and exciting signature of the Momentum 3, but also because of the improved app and the ability to manage my bluetooth connections from the app, and the ability to EQ the Momentums via the app and have it save to the headphones.
As someone who's tried and owned all the major players, Bose N700, B&W PX7, Dali iO-6, Sony 1000XM3, Shure Aonic 50, NAD Viso HP70, and the Momentum 3, the Momentum 3 is my personal favorite sound signature out of all. Notice I didn't say best. That's because they're all different. The Shure and Dalis are the most neutral and analytical to my ears. The Shure is closer to studio headphones than the Dalis though as the Dalis have a slightly emphasized bass in comparison. Nothing on this list beats the excellent high and mid details of the Shure in my opinion. The Momentum 3 and PX7 are exciting, dynamic, big, and bold, although they do this in different ways. I call the Momentum 3 a modern audiophile headphone. Very detailed while not being harsh. Fairly neutral response with a bass boost. Excellent soundstage. The PX7 are like studio monitors for your ears. They have a unique sound signature unlike any on this list. Most either love them or hate them as they definitely present your music in a unique fashion and can make some tracks sound for lack of a better word, different. I LOVE them for movies and gaming. In my opinion, biggest soundstage on this list. The NADs are very smooth. Big treble roll off but still very detailed. Just a very pleasing signature to my ears. The Bose and Sony are my least favorite sound signature on this list. Bose falls into the category with the Dalis and Shures but are no where near as refined, detailed, or natural sounding. The Sonys are a fun headphone but muddier and less detailed than both the PX7 and Momentum. Let's just say it's less fun LOL.
As someone who's gone back and forth between all these headphones over the past many months, I've settled on the Momentums and PX7. It wasn't an easy choice, but they fit my needs better. I use the Momentums as my daily drivers. I work from home and they are my Office headphones for Music, TV, Movies, and Phone Calls. The PX7 are secondary. I use them in the evenings when movie watching or gaming, or when I'm in the mood for them musically. I personally like their unique presentation. I also grab the PX7 on the rare occasion I travel.
For those that are curious, here's how I'd rank all these:
Sound -
1a) Shure Aonic 50
1b) Sennheiser Momentum 3
3a) Dali iO-6
3b) B&W PX7
5) NAD Viso HP70
6) Bose N700
7) Sony 1000XM3
ANC -
1) Sony 1000XM3
2) Bose N700
3) B&W PX7
4) Sennheiser Momentum 3
5) NAD Viso HP70
6) Shure Aonic 50
7) Dali iO-6
Comfort -
1) Shure Aonic 50
2) Sony 1000XM3
3a) Bose N700
3b) Sennheiser Momentum 3
5) B&W PX7
6) Dali iO-6
7) NAD Viso HP70
Phone Calls -
1) Bose N700 (Best in the business)
2) Sennheiser Momentum 3
3) Shure Aonic 50
4) Dali iO-6
5) B&W PX7
6) NAD Viso HP70
7) Sony 1000XM3
Features/Convenience - (The biggest convenience feature for me is the ability to manage connected bluetooth devices via the app, that's why the Momentum and PX7 are my top two. Bose has this as well but Sony has a better EQ, Sound Optimizer, and quick attention so I put it ahead. The Momentum beats the PX7 because it has an EQ and the PX7 doesn't. I do LOVE that the PX7 can still be connected to my phone via Bluetooth while gaming on my Xbox1 or PX4. Makes it so I don't have to ignore phone calls. Haven't tested this with the Momentum)
1) Sennheiser Momentum 3
2) B&W PX7
3) Sony 1000XM3
4) Bose N700
5) Shure Aonic 50
* The Dali and NAD don't matter as neither has an app, can be updated, eq'd, etc.
Overall -
1) Sennheiser Momentum (If I could only own one wireless anc headphone this would be it. Excellent sound, great features, great comfort, excellent for phone calls and is the only one that comes close to the Bose in this category. You'd just need to purchase a 3rd party case if you planned on traveling with them)
2) Shure Aonic 50 (If I was a traveling musician or used my wireless anc headphones for critical listening, these would be it)
3) B&W PX7 (Excellent travel headphone, unique sound signature, great features)
4) Bose N700 (Although the sound quality is mediocre, I can't argue that these are the best travel headphones on this list. Especially if you are on the phone a lot or use your voice assistant. Light, portable, compact, excellent ANC, good features, and the best mic for phone calls in the business.)
5) Sony 1000XM3 (Second best travel headphone on this list)
6) Dali iO-6 (I really loved the sound signature on these, however, they don't seal well which makes the sound without ANC enabled VERY inconsistent. Not enough modern features to compete with the rest
7) NAD Viso HP70