Hi there,
We use James Wellbeloved biscuits, they cost an arm and a paw but are well worth it, their coats look lovely and they always eat them right up. Two of our cats came from the RSPCA and they use James Well Beloved all the time.
My brother-in-law is a vet and their cat eats nothing but Science plan dried food, must be a boring diet but he looks well on it!
We are both veggies, but also give them Felix pouches too... I've never actually considered trying get the moggies go part-veggie too....hmm, interesting.