IMO, the best dry food for the money is probably Taste of the Wild.Here's a link
to their site.
It is grain free and is about the same price as nutro and similar brands with grains... ~ $26 for a 15lb bag (on petfooddirect.com). And is a whole lot cheaper than other grain free foods.
My cats really liked the taste of it and I'd still be feeding it if it wasn't for the fish content... Which brings up a good point. The best food depends on MANY factors... i.e. Is your cat overweight? Does it have allergies? Is it prone to UTIs? Are you feeding dry only? What age is your cat? Etc.
In my case, I have 3 male cats (males tend to be more prone to urinary issues) and one of them is very prone to UTIs...which means he should have NO fish in his diet. Because of this, I had to go with a non-fish dry food (I'm having to switch again because they now put fish oil in their new formula).
Another relavent point...grain free foods like TOTW, EVO, CORE, etc. have high amounts of protien and fat and can be quite hard for some cats to digest... They are not reccommended for older cats, cats w/ kidney issues, or for cats that only eat dry food... cat should get some wet food too to help with digestion and moisture content(easier on the kidneys). TOTW is a lot lower protien / fat wise, so is safer than, say, EVO.
Cost is also a factor. I'd see what the stores around you are carrying (make a list of brands, formulas, and prices) then research the foods online to get their analysis and ingredients online. Looking for a food with meat ingredients and little - to - no corn, wheat or other grains is a good start. Also avoiding "by products" and similar ingredients and any chemical preservatives.
Many companies will also send you samples or coupons if you are not sure if your cats will like the food or not.
Some of the other foods I've fed are: EVO, califronia natural, chicken soup (tried samples but never bought as staple food), artemis (samples, not as staple), nutro natural choice and nutro max (fed as staple, changing from max because of the fish oil), and authority (petsmart's store brand).