TE-ZX1

If sound quality is the main thing you're looking for, the AVIOT TE-ZX1 Cowboy Bebop are the best I've ever heard by some distance, and I'm coming from owning Sennheiser MTW 3&4, Sony xm4 & 5, and Technics EAH-AZ80. Only comparisons I haven't tried are the AZ100 and any of the Bose buds. For day to day use the Aviot's have issues however, the app sucks, you can't turn ANC on or off without the app, and the control buttons on the buds themselves are a bit finicky, but for out and out audio quality they're a significant step up on the above. Subjective opinion of course, everyone is different when it comes to what they like. Edit: I would also say that if you're only listening to MP3 format music, it's not going to be worth spending a fortune, you're losing so much sound quality with that format that you could get a much cheaper pair and not notice the difference.

Geekfly Legend 6, Aviot TE-ZX1, Noble FoKus Rex5. Atmos is evil.

Currently have the new pro X, they're the 3 best earbuds I've tried. They sound very clear, with a very wide sound stage, are VERY LOUD lol. The ANC is actually usable now and transparency is really amazing. Imo the only two earbuds that are better, are the fokus rex5 and aviot te-zx1, again they have 5 drivers.

SoundPeat H3 values for money. Triple drivers with 12mm and 2$ balanced armature drivers) that contributes to powerful bass, clear mids, and detailed treble, along with impressive soundstage and imaging. Other features include adaptive active noise cancellation, up to 37 hours of total battery life, IPX5 water resistance, and low-latency game mode. Proud owner of H3, Pi8, xm5, melomania A100, aviot TxZ1, devialet G2, QC ultra

Bose QC Ultra 2, Devialet Gemini 2, Aviot ZX1, Technics AZ100, and the Status Pro X isn't bad either.

I've tried many of those AZ100 for all around. Rex5 has strong technicals but just not my personal choice. Mostly because Noble's founder has a hearing aid background and expertise is in accuracy and quality, but I'm not a musician and I prefer more opinionated and engaging sound. Gemini II is like the opposite of the Rex5, while also quality, it's more opinionated and dynamic. But the tech is a little dated (acceptable but dated, BT 5.2, worse battery) I use Gemini II for on the go because it's just a put it in and enjoy. AZ100 I use for meetings at desktop because of flawless connectivity. I also like AVIOT TE-ZX1 (from Japan) that has the same driver config of Rex5. I would frame it as in between Rex5 and AZ100 and I would recommend it too. Not sure if you can get it in the USA still.

Purely for sound you're looking at the Pi8, Rex5, Vitas and TE-ZX1, but which of those you like best will depend on your preferred sound signature. All of these buds are focused purely on sound, which means multi driver arrangements with specific placement and airflow have been prioritized over things like mics, noise cancellation and other features that can compromise sound delivery. For solid all-rounders that do everything fairly well without being outstanding in any area, it's the usual household names - Sony, Huawei, Technics, etc

Well OP did want the best sound quality. The better TWS are surprisingly good, I paid 220€ for my Aviot TE-ZX1 and they're definitely better than most over-ear ANC headphones at least in that price range. You can't really get anything better for 500 bucks, maybe the new Sennheisers, but I haven't heard those.

I love my Aviot TE-ZX1.

Well obviously when you're talking about wireless audio, latest technology is better than the old. The amount of tech that companies are currently able to fit into an earbud is insane and the true wireless scene is just getting more advanced. There's literally no reason for me to reach for an IEM when I have the Aviot TE-ZX1 TWS. There's nothing a sub 500$ IEM does that can't be achieved by a good TWS.