Thinking of buying 1 of these fods for my bordeaux which do you find the best. Opinions please

I loved RC - well my dogs did!  But they got a bit outrageous pricewise for someone with a lot of dogs.

Every time I have tried Pro Plan, it has, without exception, given my dogs the most awful diahorrea.

I found ProPlan really greasy-feeling and my dogs put on too much weight with it. 

Royal Canin has maize in it and I wouldn't feed that (now) and also has too much rice for me. 

IMO for the same price as those foods, you can feed something far superior to either of them - there are many foods which are better.

I fed one of my dogs Proplan for years and she was great on it. Then they altered it and it became really 'fatty/oily' - slimy to the touch and the bags it came in began to leach some fat/oil through the surface. Not pleasant at all. Sadly, it no longer suited her (upseting her tummy) and after sticking with it for a few bags longer (just incase it was a blip) we were forced to stop using it. Incidently, I have never been able to find a food that suited her as well as that original proplan.

Have also fed RC (to both dogs and cats) and was very pleased with the results, but found the cost was prohibitive over a long period of time.

I raise all of mine on RC and I love it but like others, you can feed better for cheaper and that's with the breeders club discount and everything!  I find PAH deals are a bit cheaper for RC.

The pups in my last litter have had RC (the ones not raw fed) and have grown really nicely (giant breed).
I agree it is expensive for what it is and I would not feed the adult versions to my adults as better foods around. The reason I went for it for the litter is that when you know of hundreds of dogs of your breed growing nicely with it and having good health results it was kind of a safe food to use opposed to using a different food not so widely used/less experiences.
It is also easy to get hold of, another criteria when thinking what food to put a litter on.

We fed Royal Canin for many years to our Boxers and Frenchies, they all did well on it until they changed the recipe slightly, tried Pro Plan and it didn't suit the Frenchies at all (extremely loose), changed to Fish4dogs about 3 years ago and have never looked back. Lovely coats and solid poops (like pebbles).