I can't really tell you which is the best. I like CSJ because it is a small UK company, I know the owner and her integrity and high level of customer service and it is slightly cheaper than most other high quality food as it is working dog food hence VAT free! They also have a big range of various foods (check
www.csjk9.com) so there is normally something for every dog.
Burns is definitely a good one too and more readily available than CSJ (which can be bought from stockists and on-line only), James Wellbeloved is ok but belongs to the Master Foods Group that test on animals (though JWB itself doesn't), so personnally I don't really want to support them.
You'll have to try what suits your pup, not all good quality foods suit all dogs. Jesse was on CSJ CP27 until 4 months old, then on CSJ CP21. He is now on CSJ TurDucKen as it is gluten free and seems to suit him more than any of the others.
Vera