Is Blue Freedom or Blue Basics better to try for a cat with a sensitive tummy? I really want to get him off that vet diet Royal Canin with the crappy ingredients but every time I try he goes back to the diarrhea. (and yes I transition slowly).
Yes I think Merrick LID is a good choice too. BB is garbage food, skip it.Merrick LID is a good quality and simple, easily digested food that I recommened.
That bolded phrase is the key point for feeding a cat with a sensitive stomach. In our case, a cat has a problem with potato, a very common filler ingredient. Wet foods with simple recipes--preferably without carby ingredients or carrageenan--are the easiest place to start. I admit that there aren't a lot of those foods, but the combination of high-protein and low-carb is what fits cats best anyway. And Fancy Feast pates, which are very available, are a very decent place to start! (With a sensitive stomach, I'd also avoid fish but FF does have a bunch pates without fish, too.)
If your has a sensitive tummy, you need to figure out if he's sensitive to certain ingredients in whatever other foods you were feeding that the Royal Canin does NOT contain, or if it's a specific protein, such as chicken, that he is sensitive to. Looking at the Blue Buffalo Freedom dry food, I see a lot of things in there I dont like either.