He is a black German Shepard mix, 90 pounds, and we adopted him 2 years ago. We tried Blue, Wilderness, Wellness, Merrick ... he didn't like it, some gave him diarrhea despite very slowly introducing it to him, and some he just constantly threw up. I don't know how much money we threw away. We tried the Costco brand and it was alright for a short while.
Then we tried the Purina One SmartBlend with Turkey and Venison and he loves it. It has 30% crude protein (more than the cheap brands) but it also has corn. I'd rather have him eat and not throw up or have diarrhea. I really don't mind spending $50 for a bag of premium dog food if he'd eat it, but he never liked any of them.
As with any new food, very slowly add it to his old. Our dog eats 4 cups a day right now and we started with adding 1/8 cup, increasing it every couple of days by another 1/8 cup. No more diarrhea or throwing up and he loves it.
From a nutritional standpoint, Blue is MUCH better than Science Diet. If they like it and you can afford it, I'd continue. Someone posted the link to dogfoodadvisor and it is a really good point to start. Sadly, my dog's taste buds didn't agree with the ratings 
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