You're going to get lots of different opinions, and I personally don't think any manufactured food is going to be the only thing you should feed your dog for the rest of his life. I like to vary between one or two brands that my dogs can handle without getting runny poops. I wouldn't vary it daily, but rather maybe make a switch once or twice a year.
I also feed on meal of cooked meat (either chicken, beef, turkey or pork) every day. Snacks are fresh fruit or veggies. Sometimes I will roast veggies to add into the meat meal.
GSD's tend to have sensitive tummies. I would make first priority finding a food that works for your pup.
I've never used Nature's Logic for my dogs, but the name is familiar. If they have a cat food line, I probably fed it to my cats at one point.
Niko: American Showline GSD 5 years old
Rosa: American Muppet Dog (GSD/Border Collie mix) 5 years old