Which food for which dog?

I need food recommendations. I have 2 dogs, a 6.5 year old GSD named Xander, and an 8.5 month old toy poodle named Fred. Currently, Xander is eating the Costco brand (Kirkland) brand of adult dog food. He's on the chicken formula. Fred is currently eating Chicken Soup for the Puppy Lovers Soul. I don't have very much income so I can't afford more than about $25 of per month per bag of kibble on Xander. For Fred, I want to buy in bulk so I only have to buy every 3 months or so, since he's so small, but I noticed that Xander eats a large bag a month. Now, Xander is on the skinny side and still hyper so I don't want to switch him to a senior kibble. But I do want to switch Fred to an adult kibble since he's pretty much reached his adult height. I just want to know what would be the best food for each dog keeping my budget in mind.