It's tough work finding pet food that isn't crap. There are very few regulations regarding what can/can't go into it and many of the so-called "premium" foods are junk loaded with fillers (like Chinese gluten which killed hundreds of pets a few years ago), rice, corn meal, etc.
Unlike humans, cats require certain amino acids that they can't metabolize and which can't be derived solely from plant sources (humans OTOH
can manufacture 100% of what we need from plant-only sources). Felines must get them from their diet - and that means meat sources. I don't particularly like it but that's just the way they're made. Nature of the beast - it isn't their fault.
I've had good luck with Nutro Natural Choice (one of the few brands not tainted by Chinese gluten - but I still check occasionally to make sure they're not cheaping out and starting to slide it in). Keep this in mind - pet food manufacturers can radically change the composition of their foods with little or no notification. Here's a good resource about some of the things to be aware of:
Understanding Pet Food Labels | Veterinary Medical Center
The Nutro N.C dry stuff is usually good, I give them cans (wet stuff) a couple of times a week as a special treat also. Greenies are decent treats too. I also use Natural Blue treats on occasion, which they seem to like. Generally if something contains rendered anything, rennet or loads of rice or corn I skip it (pretty much everything in Walmart and similar places). A few of the "mass produced" foods actually do seem okay today though - you just have to look and carefully read the ingredients and understand what each thing means (wording and order of listing is important).
You really have to do your homework and realize that nothing is ever static too - foods that are good today can be junk tomorrow and vice-versa but there are some that seem to hold up okay over time. In the case of the Nutro Natural Choice they HAVE cheaped out a little (more filler) in the last few years but I find it to be a decent product still. I'm certainly open to new ideas / discoveries by others out there. Your mileage may vary.