Just gonna give my opinion on each member. I think they can generally pull of everything but some hairstyles are better than others.
For Jungkook dark brown or black is best. Jungkook's hair was pretty bad during BIL era imo. He suits longer, messier hair in dark colors.
I think Jimin also suits dark hair. His orange and red hair was cool and looked good, but black looks even better. Also unpopular opinion but I don't like when he parts his hair. Danger era haircut where we could see his forehead but he didn't have a part was best, but fringe is also nice.
I like medium brown hair on Jin. Dark brown is also nice. I hated his purple hair the Danger MV.
V looks good with both light and dark hair. The only hairstyle I havent' liked on him was the one in the NMD MV. The color was fine but the cut didn't suit him.
I've loved all of Suga's hair colors except the orangey one in WOH and the red in Danger. The cut in Danger was bad too. I think he suits a longer, slightly messy fringe. And mint was the best color he's had so far imo.
J-Hope hasn't had a ton of hair colors, so from what I've seen black or brown is best. But his best haircut was by far in NMD. We need more forehead.
RM can rock grey hair. I didn't love the pink for some reason but white and grey hair look great on him. I also think it can be cool when he has light hair and his roots are showing.