SuperTed,
Welcome to the forum..:-)
These are a few brands which I personally like. Simply from reading online seems good as it is Gluten Free, so a lot less filler. For me RC is not what I personally like for mine, but so many dogs out there do very well on it.
http://www.bernpetfoods.co.uk/ - Orijen is a huge favourite in my house when the pennies allow. Acana has also gone down a treat when we won some at a show. Ziwipeak is mega expensive but i'm sure ruddy brilliant.
http://www.ardengrange.com/ - They have a nutritionist there who can advise on what is the best food for your dog. Also coat appearance and skin have a reflection on what you're feeding..
Or you could go for it and do raw food?
Each dog will accept foods differently, so its trial and error. A good way is to keep check of their weight and make sure there is not a huge amount of output. The colour of the poop also is worth keeping tabs of.