A Arai, Shoei, Shark and AGV are the big 4 helmet brands and yes, probably the best motorcycle helmets you can buy.
Schuberth are extremely good too but we recon the styling isn't as good as Arai or Shoei.
Of course fit is critical – the best motorcycle helmet for you is the one that fits best so try some on in the shops and don't make up your mind until then. Also, do not buy a specific helmet brand because your friend has it. Our head shape is unique, and your head shape is likely different than that of your friend.
After a year with a cheap helmet, I've saved up enough to get a top-of-the-rang one. You seem to get to try plenty so what should I go for?