Audio Technica ATH-CKS5TW
Right at the bottom of this list, we have this.
Now, you know think that a company like Audio Technica, the one responsible for the massively popular M50X, would naturally have the capabilities to create at least a decent true wireless earphone. But if the CKS5TW is any indication, they should just stick to their wired stuff instead.
The main issue with the CKS5TW is the deadly combo of a massive, uncontrolled bass boost (that smears all the way into the midrange) with a near-nonexistent treble presence. It is a muffled, dark mess that doesn’t even have the redeeming quality of a natural midrange tonality; it’s just bad compounded on bad.