I've been mostly keeping Frisky Bitz in my bowls because I want to save my gold fish for other things. Will I be able to collect all the kitties with this food, or do some kitties have more expensive tastes and only come for things like Bonito Bitz?
Offering more expensive cat foods, along with specific toys, will attract rare cats to pay a visit. More expensive cat food will also simply attract more cats in general.
The most obvious example of cats who are after food that costs money is Tubbs, who is only interested in food, and will only show up to eat (an entire bowl) of any food that costs money (fish).
Other rare cats are interested in playing with specific toys, and having expensive food around will increase your chances of coaxing them out to play with those toys.
Some rare cats will only show up when using specific foods or toys. You can find an incomplete list of which foods attract which cats on the Neko Atsume Wiki.