First time cat owner: what’s the cleanest/healthiest wet and dry food that’s still somewhat affordable?

I just recently got my first cat, and I’d like to give him some better stuff. He’s currently eating IAMs proactive health, and I got him a few cans of Friskies. I just feel like that’s probably not the best for him, but I don’t really know. I do put some fish oil and probiotics in his food at least, as that’s what the rescue recommended for him.

Any advice would be greatly appreciated! I want to take care of this sweet kitty and have him be happy and healthy.