If you have to do kibble go with Orijen, pricey, but you can feed less.
Real name meat sources, no preservatives like BHA, BHT, ethoxyquin.
Raw really is best, but can be pricey or laborsome for some. There are commerically prepared raw on the market that depending upon the size of the dog isn't too pricey.
I just lost a dog to cancer, and have read a lot on the subject.
I'd also recommend 1g of fish oil per 10lbs of dog (liquid fish oil is easy to add)
also get Curcumin at 1-2g/day
1:3 dogs die of cancer, and those 2 supplements are critical for that in prevention and treatment along with other health issues.
I'd also suggest checking out pro-biotics and especially digestive enzymes if you're going to feed kibble.
Good luck, I'm doing a nutritional seminar soon on dog food/vaccines and the like. Hit me up in a month and I'll send you the video for free if you're interested, or you can pick up some books on the subject.
EDIT- if you have a breed prone to heart issues, depending upon age I would also look into 100-300mg/day of Ubiquinol (better form of CoQ10)