At the end of the day you need to feed what suits your cats and what they like. Just like people they have preferences .. like some flavours more than others, prefer wet over dry or jelly instead of gravy. Some will just eat anything.
It's so easy to say oh I only intend to feed them the high quality stuff .. but if they don't like it then its not good food for that particular cat. I do actually get ever so annoyed with discussions like this. My boy eats a variety of stuff including Whiskas, Sheba, Felix and Hills as his main food. He is sleek, very active, very healthy has great condition and his coat is gorgeous. He's this way because his food suits him. Feed him hi-life and he is
always sick. Whilst he likes applaws wet he doesn't love it and would eventually get bored of it. Therefore they are not good quality for
him.
Just like people they have different appetites. So feeding guidelines are just that. Taking my boy as an example he probably eats 1/4 of what would be recommended ..a) he just wouldn't eat any more and b) if he did he would end up morbidly obese
What I would do is stop offering different things (creates fussy cats if you keep offering new things when they don't eat something), stick to one thing that they do like. Offer them the amount of food that they eat, if they seem hungry later offer them some more. They might not be eating because they are full.
I think what it comes down to, you could read all the nutrition/food related stuff, buy all the expensive 'high quality' food, buy a new freezer and fill it with raw .. or you could just listen to your cats and go by them.