I can see how a lot of dog owners are tempted by the marketing of certain brands thinking the more expensive the food the better it is, maybe? One of my friends started buying a make that the makers marketed as made from natural spring water and was charged the earth for it, my dogs drink from stagnant ditches so I didn’t think it would make much difference to them!!
I swap and mix the feed for my two as they seem to get bored the same one after a while. Always dry but mixed with juices from roast meat, tin toms, beans, anything moist really. I know its one of the cheaper ones but DR Johns Silver seems to be a favourite. 10year old and 5 year old, touchwood both still as fit as a butchers dog.