majority of the economical biscuit brands (typically with cereals as main ingredients), also many of the fancy looking wet food brands like shiba, fancy feast etc., add flavourings and extra fat in order to make the food more appealing to the cats, while their nutritional quality is subpar. It's like a junkfood, okay occasionally, but not ideal for a regular diet. I would stay clear of them not to get the cats too attached to them.
Oliver turns his nose up at very delicious looking (even to me!!) almo nature main series
but he does love their bio patè (tuna-sardines, tuna-chicken, tuna mackerel), which became his staple. I wish there were more variety in flavours I am worried he may get bored and goes off of it after a while!!