I totally understand your confusion - there are so many products on the market these days. Luckily, the Dog Food Directory
of this website simplifies things considerably if you spend a bit of time getting familiar with the filters on the left hand side of the page. This is how I have evaluated the products that I have given my dogs and I have learned a lot in the process. I always select no red ingredients right from the off and that immediately brings you to the better quality products.
Your dog is very young and if you learn a bit about The principle of selecting a good dog food
it will stand you in good stead for the years to come. Have a look at the linked thread and you will see that it is not as complicated as you might think.
Royal Canin contains some controversial ingredients but there must be plenty of dogs doing fine with the food. If you feel that your dog is doing well on Arden Grange and you are a keen cook, how about sticking with it and topping up with a home cooked meal? Rodney Habib is a pet nutritionist blogger and he talks about this here.
Of course you need to read up in order to be sure to give the right sort of food but it is not that difficult.
When thinking of products that are not extruded (manufactured using high temperatures), as well as cold pressed food you might want to consider raw complete products if you have freezer space. There are also air/freeze dried raw but they are expensive AFAIK. Most raw complete foods score very highly on the Dog Food Directory. Examples are Honey's, Natural Instinct, Natures Menu, Nutriment.