Defo go for Canterbury. All the pros wear them. They have the best protection and are comfortable. I would reccomend the Canterbury Ventailator. It comes in loads of colours and is comfortable. If you look on TV most of the best players have them. A good website for them is Lovell Rugby Hoped that helped.
It depends on your choice, if you want more colors and collection then go with Canterbury Ventilator. If you want to purchase long lasting rugby head guard then go for Adidas.
Here is a list of the best head-guard from each brand: adidas - Pro Rugby Headguard II (worn by Matt Giteau, Leigh Halfpenny) kooga - Any Kooga shadow Headguards mainly either 2 and 3 Gilbert - Xact Headguard (Worn by Thierry Dusautoir, Berrick Barnes, Todd Clever and Tom Palmer) Puma - V-Konstruckt Canterbury - Airflow or Ventilator In professional Rugby the pro Rugby Headguard by Adidas and the Xact would be by far the most popular. pro-Direct Rugby is a great store to buy from as well. I hope this helps.