I reckon the hanger steak is the best flavoured of all steaks.
The French call it "onglet" and it is commonly served with French fries.
However, I do not believe that a simple BBQ is the best way to cook it.
I prefer to "sous vide" it for 12 hours at 55C (132F). Use immediately OR store in fridge for few days OR freezer long term. When required if BBQ on I give quick sear at hottest possible temperature alternatively I sear in very hot skillet.
Tendered than fillet and massive flavour. I provide a link to what I believe is one of the best article on cooking steak including a hanger steak recipe.
http://www.seriouseats.com/2010/03/how-to-sous-vide-steak.html
John