This is such a complicated question lol and you could end up with a ton of different answers. People tend to feel very strongly about their feeding choices but I think it really comes down to what works for you and your goals for your flock and also the make up of your flock.
I would start reading all of the feed labels so you can get a good idea of what your choices are and how the feeds are different.
A standard commercial layer is made to be complete nutrition for a laying hen who is laying eggs regularly. They vary a bit from brand to brand but will be around 16% protein and have the extra calcium already for egg shell development. This is the most commonly fed food. It is an easy all-in-on, cheap, and your birds and eggs will be fine on it.
That being said it may or may not be the "right" food for your needs. If your flock is mixed with roos, young bird, molting birds, old birds, breeds that lay infrequently, etc then the layer feed is not ideal nutrition for these non-laying birds. They will be getting too much calcium. It is not as bad for roos and older non-laying birds but I would avoid it with young pullets and chicks. An alternative is to feed a grower or flock raiser (you can find these anywhere from 15% to 20% protein) and then offer a calcium source, like oyster shell, free choice separate from the feed. Chickens are good at regulating their own nutrition if given good choices and will only eat the calcium if needed if it is separate. It is up to you. Some people feed their laying hens and roos a layer all year round and are happy with that.
Also, all commercial feeds are non-organic GMOs. This may or not be an issue for you. Most standard commercial feeds are made with a soy protein base. This may or may not be an issue for you. Some people prefer an animal based protein source - the one I personally see the most is fish meal.
If they are getting all or almost all of their diet from feed then the 16% protein in a standard commercial layer is good. If you they giving a lot of scraps, scratch, greens, fodder, etc and it is making up good portion of their daily in-take you might want to consider a feed with a higher protein (18%-22%) to keep a good balance.
I personally feed a 20% protein starter/grower that is soy free/corn free with a fish meal base. And then grow an organic barley/wheat/BOSS fodder mix and give them a brick of sprouts everyday. I see a noticable difference in the color and quality of my egg yokes when I started the fodder diet. I choose this for the quality of ingredients and some personal and political reasons and because my flock is very mixed it age and breed. It's right for me but I recognize that is is expensive and a lot more work and to drive much further to find it - and it is not really necessary per say.
Good luck!
https://www.backyardchickens.com/t/713334/growing-fodder-for-chickens