Neither go cat or Felix are all that amazing tbh.
If you look at the ingredients on the side of the packaging it'll give you some indication. With Felix and go cat it'll say ''meat and animal derivatives- min 4%" this means that say for example you have chicken flavour it could be less usable chicken protein: eg feathers, bones, skin and can even be other meat- pork, beef etc. The recipe doesn't remain consistent as it depends what the manufacturer has at the time. Sometimes meat content could be 4%other times more.
Look for flavourings, colourings, cereal derivatives. Any decent pet food shouldn't contain these things.
If you can get them onto a decent dry food this will help with the skin (won't be as oily), teeth (as dry food doesn't stick to the teeth unlike wet) and the end result (what is fed wet comes out wet).
James wellbeloved, royal canin, pro plan, science plan, pets at home advanced nutrition, applaws, purely, wainwrights cat are all very good brands. If you have a pets at home near you and you buy their own branded products (advanced nutrition, wainwrights, purely) and your cats don't like it you get all your money back, even if the pack is open.