You are just used to a V-shaped sound with mediocre technicalities. If you’ll listen to focals/660s for let’s say 5 days, you will get used to them and after that your airpods will sound like absolute shit to you. It’s always like that. But it’s up to you if you actually want to give it a try.
P.S. they sounded „quiet” to you most likely because of their relatively flat response. Also it is worth to note 660s need an amp to sound properly.
I’d day Apple, Samsung and BOSE are the least problematic