It depends what budget you are in and what you are looking for.
Generally I’d say in the ‘affordable’ category i.e < $200:
Audio-Technica is generally the leader in this category and makes many great low cost headphones like the popular M50X. Sennheiser/Drop 6XX is also a very good pickup in this category as well, as is the Beyerdynamic DT770 Pros and Grado SR225 and AKG K702. The AKG, Senns and Audio-Technicas I think are all great for studio reference type of sound. I think V-Moda and Klipsch make some nice earphones in this category as well but I’ll recommend the SeeAudio Yume II, HiBy Lasya or HarmonicDyne Devil here for IEMs. When it comes wireless earbuds, I think the Final Audio ZE3000, Marshall Motif and Klipsch T5 IIs are all nice for the price too.
In the mid-range category $200 – $500 it gets very crowded as this is the competitive market for mainstream consumers:
Great noise cancelling headphones like the Bose QuietComfort Ultra or Sony 1000-XM5s can be found here, but I’d recommend the Bowers & Wilkins Px7S2 or Sennheiser Momentum 4 or Audeze Maxwell as my pick for wireless headphones in terms of sound quality. For wired over ears, I would recommend the Beyerdynamic DT1990Pro as it’s a great headphone for most types of music as well as gaming (my pick for open back), or the Sennheiser HD650 for a tried and true classic audiophile headphone or the Dan Clark Aeon X Closed (my pick for closed back). For wireless earbuds you can pretty much get the top of the line here, Sony WF-1000XM5s are popular, but for the best sound quality I’d recommend the Master & Dynamic MW09, Final Audio ZE8000, Audio-Technica TWX9, Noble Fokus Mystique or the Devialet Gemini II, all of which sit at the top end of the wireless earbud category. For IEMs, Dunu ES112, 7Hz i99, Shozy Magma, Final Audio B3 are all nice for this range.
In the high end category $500-$1500 we have even more great options of course:
For wireless, there’s the Focal Bathys, Mark Levinson 5909 and Bowers & Wilkins PX8. For wired closed back over ears, I’d recommend the Fostex TH900 for bassheads, Audio-Technica AP2000Ti for trebleheads, Fostex Th610 for vocals. For wired open ears, I’d recommend the Hifiman HE1000 V2 or Sennheiser HD800s for soundstage, and Focal Clear for nice midrange. For IEMs, ThieAudio Divinity V16 and UM Mest MKII are my recommendations here.
In the super high end category $1500+ the sky’s the limit here:
Some of the best headphones to exist are in this price range. The Hifiman Susvara, Focal Utopia, Audeze LCD5, Audeze CRBN, Stax X9000 (my personal fav), Dan Clark Corina, Meze Elite, Meze Empyrean II, Final Audio D8000, Denon D9200, Sony Z1R, Audio Technica ADX-5000 etc it all comes down to which sound signature you prefer at this point.
And for TOTL IEMs, There’s the Noble Viking Ragnar, Empire Ears Raven, UM Mason, Softears Enigma, Vision Ears EXT, Elysian Annihilator etc truly the best of the best are here.