Agree that there is no one answer that would cover all cats.
Have an older cat now with vomit issues that, according to the vet, is probably allergic to most grains. So that one gets a grain-free diet. It took a while to figure that one out. Puking with hairballs- normal but it doesn’t happen every day or even every week. Allergies might be one reason to go to a grain-free diet.
Since the above cat is also prone to eating too fast and gorging food, the second cat is also on grain-free and have seen that one get sleeker as a result, just an observation.
But, the second cat gets a grain-free kibble twice a day while we try to restrict the other to canned food only. If the older cat gets hold of kibble, it will come back up as a general rule. So, for whatever reason, kibble will cause puke in the one cat. We feed the other cat only the amount of kibble it will clean up, so we don’t have to stand guard while they are eating to make sure the gorge monster doesn’t get hold of it.
Both cats get a canned food “snack” at lunch time and before bedtime. That’s also because we don’t want the older cat to try to eat too much at once- because that one sees it as their duty to clean up every little bit it can find. 
Although the vet recommended a presription diet for the one cat, no grain, with some not-so-common protein- duck, rabbit, venison- we’re currently feeding the Wellness grain free canned and actually having better luck with it. The kibble for the other cat is From the Wilderness grain free. It’s more expensive but I’ve found we feed a lot less of it, plus it’s not all of the diet for that one.
YMMV. For us, it was issues with allergies to any grain, and the older cat’s attitude about cleaning up any food it can find. (The other stuff in grain-free will be vegetable based, usually) Obviously, we don’t leave out food for them and they seem to do just fine. You might also consider smaller feedings and more of them, if you have the time. Right now we have enough people in the house with enough different, odd work schedules, that getting that “lunch” treat in is not an issue.
Both cats are indoors only cats.