We had Samson on Royal Canin, but noticed that it does have lots of fillers, so we just switched to Canidae and he LOVES the food. He licked the bag before we could open it, he was eager to give it a try. Plus, I have noticed that his stool is much firmer and more compact. We do give him some Alaskan salmon oil for his coat and some plain yogurt for his "gas" issues and I must say the combination has been wonderful.
Definitely do your research, this site has great resources. But all dogs are different and react differently. Some may have allergies to certain meats and certain grains, so if you have a dog who has a sensitive stomach or allergies sometimes a food with one meat source and one grain source would be recommended.
But it is great that you are taking an interest in what your boxer if fed, especially with the food recall that is taking place right now here in the US.