I think it is a combination of the helmet and his attitude. U cant ever see his expression, and hes always got this coldness to his voice. Hes pretty much a badass. But yeah his helmet and armor are my favorite part about him.
Bossk would probably have to sneak up on boba to kill him, and he would probably use his claws and teeth
battlefront is the best, republic commando, kotor 1, and bounty hunter
I say Darth Maul becuz he was one of the sickest bad guys ever to grace the galaxy. He would destroy vader, i think maul is just too quick for vader