Teenagers are mostly into gadgets and electronics these days. To be on the safe side, I usually go for a gift card so my niece and nephews can get a present of their own choice. You could maybe get their favorite video game? Or if they’re into anime, ask them about their favorite show and get them a character-themed t shirt, I am sure they will love it. I got my son his favorite Goku black t shirt, and he never takes it off.