If you’re looking to not deal with a wire…you won’t have a great time with either the M40X or M50X. As you said, you could use a bluetooth adapter, but I’ve never personally thought that was a great solution.
The AR5BT and SR6BT are essentially the same pair of headphones, just marketed under two names in different parts of the world.
None of the headphones you mentioned are top tier for comfort, and all of them will touch your ears while you wear them. I think the M50X is comfy, but I’m in the minority on that one.
I’m also guessing that those songs you secretly enjoy have a lot of bass. None of the Audio Technica models have very aggressive bass. They excel in the upper midrange, and are best for classical/jazz/female vocals.
In the same price range as the SR6BT…I’d probably start my search with maybe…the Sennheiser 4.50 BT? They have noise cancelling and were recently dropped to $149. Or if you don’t need the ANC, you could go with the 4.40BT for its new price of just $99.
Hope that helps you out!