Chicken Soup is a very good food, but personally I think it's 2nd tier. Don't panic, it's nowhere near the junk food brands, but it's just a pinch below California Natural and Innova and Innova EVO and Felidae and such. Such a small bit below that many people are debating about it: is it top of the line or just a pinch below?. I wouldn't mind feeding it, if my Molly wasn't already doing so well on Timberwolf Organics (I tried many foods and was about to try Chicken Soup when I found TO, which seems to be the magic food for Molly). Chicken Soup is loads better than Nutro and even more eons better than Eukanuba (which is bottom of the barrel, IMO). I wouldn't mind trying EVO, simply because I believe in variety, but if it doesn't work, head right back to Chicken Soup, lol (or try plain old Innova, which might work better than EVO).
I think that if your cats are doing so well on Chicken Soup, don't switch. "If it ain't broke, don't fix it." That's my favorite motto, and everytime I ignore it, bad things happen. They do well on Food A, for example, but I want to experiment with Food B. Food B gives the animals bad gas and diarrhea, so I put them back on Food A. Unfortunately, Food A no longer works at all well so I have to look for a whole new food.
Foods that are good are:
Chicken Soup For The Pet Lovers' Soul
Flint River Ranch
Blue Buffalo (Spa Select, though I like the cans better than the dry)
Merrick (cans are top of the line, though I think the dry is a little too grain-heavy)
Nature's Variety Prairie
I want to someday put my cats on a RAW diet but for now, they're on dry with as much wet (canned or raw meat) as I can get. I worry they aren't drinking enough, and Willow already has issues with her bladder (no UTIs that I know of, but she likes to pee out of the box pretty often), and Molly could really benefit from a raw or all-wet diet (her poops stink to high heaven and she's starting to gain weight). But it's Buffy that's slowing us down: I give her meat, and she gives me a distainful look. She likes cans, though, so that'll obviously be the first step.
Raw can be fed manually (you buy the chicken or lamb or whatever and chop them up yourselves, and feed them the proper amounts). It's the most taxing, both time-wise and money-wise, so those who don't feel ready for that (I personally am afraid of feeding the wrong portions, like too much muscle meat and not enough organs, for example), and in that case, there are premade raw meats. Nature's Variety Prairie seems to be a favorite on this forum, they have a RAW line that I've tried once. I have my own favorites, though; my girls tried the Prairie but they didn't quite respond to it (it looked funky to them, since they're more used to mushed, ground up types that I prefer to give them). Some are in the forms of medallions (like Prairie) which can make them more convenient to feed, but like I said, my girls didn't like it much. The outside of the medallions are a different color, from the cooking process, and I've found my girls don't really care for frozen/cold cooked meat. I prefer a different brand (of which I can never remember the name of, lol) that comes in little containers, and the meat is all ground up. I let it thaw out and then spoon out portions for my girls, and they eat like savages. RAW can be in different formulas, like canned food and dry food. The brand I like best (of which I can't remember the name of
) has several different brands, like Chicken, Lamb, Ostrich, Duck, and I think Elk? I haven't tried the last brand, but the cats go crazy for Chicken and Lamb and Duck, though they had a hard time liking the Ostrich. I ended up giving it to my dog, lol