Does anyone feed their German Shepherd Royal Canin, is it better than Acana? And a worthy switch?

My German Shepherd (6 year old) has been having non-stop diarrhea ever since I went on vacation and he was in my families hands. My sister took a photo with his poop being all mucus-y and blood. They took him to two vets, both who weren’t really concerned about him, gave him a shot — and GI food.

We sent for a poop sample, it’s been a few days; still awaiting the results.

I’ve tried the bland diet (chicken & rice + I’ll ad 12 tbsp of turkey broth) for several days now, maybe about a week. He’s been obviously starving on it (devours it, but still hungry after.)

His poop was less consistent in terms of diarrhea less times a day, instead of doing it more than 3x plus per day. Still mucus-y, and not fully or actual solid.

The last time he was solid was a few weeks ago when I returned to my trip & gave him chicken + rice, it was solid so I’m not sure why it’s gone back to diarrhea.

I feel like Acana has been a garbage brand for him, now I’m hearing about the awful heart issues (or something of sorts?) It’s been known to cause. He always spits the kibble out too. I’m thinking of switching him to Royal Canin at some point once I can get stools softer.

Is Royal Canin good brand to feed or will it cost more issues?