I'm going to assume you mean M2L? However I am not going to assume whether you mean in bed or in a fight... so:
Jimin - His go to move, you can't convince me otherwise
Hoseok - Likes to use hair for leverage to get the upper hand... he also bites
Taehyung - Uses it as a means of escape if he is cornered
Yoongi - He knows it hurts, that's why he is doing it. Usually because the fight has gone too far
Jungkook - Can and will over power you with his body the large majority of the time
Jin - Scared you will retaliate. He has done a lot to his hair over the years and prefers it be left alone now. Don't go for his he won't go for yours
Namjoon - This man is too tall for a low blow. But seriously I just think he prefers to fight fair.
Least (Please be aware when I say least the B in BTS still stands for betrayal so it is not completely off the table for any of them)
Hoseok - Gets genuine pleasure from seeing you cringe when he tugs too hard. It makes him so hard when the tears form in your eyes. Similarly he wants it to feel like you are on sharp tug away from pulling the strands from his head
Namjoon - Loves the authority, Uses it to pull you onto your knees sometimes. Makes you look at him when you get shy. For the love of good play and pull with this mans hair, he will love you forever, becomes submissive putty.
Yoongi - Not so much pulling, more using it as a handle. Guides you where he wants you to go Dig your fingers into his scalp and he will purr
Jimin - Pulls when he cums, his fingers dig into your scalp as he releases down your throat or from behind.
Jungkook - Prefers using brut force. He is not working out for the aesthetic. Pull his hair and call him pretty though.
Taehyung - Too busy grabbing at you everywhere else. Likes to leave bruises on your hips, finds it a much better use for his hands. Prefers your hands are wrapped in the sheets physically incapable of doing anything else
Jin - Finds it degrading. He is more into intimate sex. Praise kinks and choking. Your hands should stay around his neck, his should be pleasuring you.