Otherwise, better quality, prices, and service (and staff pay and treatment).
But it's taste, I suppose.
Nobody is forcing you to go to McDonald's, stick with INO if it makes you feel good. I love it too (CFA, not so much) but each restaurant has its own niche and each chain has found the style that works for them.
And this is exactly the source of the problem: the idea that the purpose of McDonald's (or any other company) is to provide Number Go Up thrills to its stockholders, rather than to produce a good product, with the profit being the reward for doing so well.
McDonald's goal isn't to produce the greatest burger in the world. It succeeds at the best combination of pretty tasty food, high menu variety, very convenient, generally quick, and low price. It is not #1 at any single attribute (maybe convenience) but the best overall combination.
Interestingly, Chick-fil-a has learned to scale and maintain quality.
Every INO is company-owned, overall I think it manages to keep quality pretty high at all it's stores. Of course part of that is due to the extremely limited menu, and also that INO has never been known for fast service. INO basically tells customers up front, we aren't convenient and we aren't fast and we don't sell anything except burgers... that's 3 areas of potential customer dissatisfaction that they take off the table. All that is left is price, which is good not great, and taste/quality, which, to its credit, INO is pretty fanatical about. Edit: and cleanliness/service, also strong points for INO
I think a better McDonalds looks a lot like In and Out. If the Founder is accurate, McDonalds was a lot like In and Out at one time and operated like it. Chick-fil-a operates similarly.
One thing that is always fascinating to me when I go to either of those two fast food restaurants is the army of workers they have on staff at any time. Usually each doing one very specific job and doing it well. They seem to make up for the extra labor cost by having higher sales per store.