I don't like either Felix or Whiskas, the meat content is low and there tends to be a lot of soya and cereals, even in the Whiskas 'oh so meaty' range - it's not really that meaty at all!
I am assuming that as you mention Felix you are in the UK? Generally speaking most supermarkets do not carry a great range of good cat food but will have a wide selection of junk food for cats. Try pets@home and look out for Hi-Life and Nature's Menu (some of the large Tescos have those but not all of them) - they have a good meat content and no nasties. Check ingredients - if the first ingredient is anything other than a named meat, or if the meat is only a low percentage of the meal, then the food is not a good food. Nature's Menu contains 70% meat (chicken or beef), not meat by-products, so that gives you an idea of what to aim for
Online pet food suppliers such as zooplus have a good range of high quality foods at good prices.