I think Skyline and Gold Star were omitted because they are large chains. The rest are single "parlors", a few have 2-3 other outlets, maybe.
We'd go to Blue Ash Chili mainly for various reasons including location. Folks swear by one or another but they all taste about the same, to me. I find it interesting that you have such a concentration in Cincy and so few anywhere else, I think there are some dotted around in Florida now, and some in Columbus, Ohio. But they are everywhere in Cincy. There was one near where I worked called "Cretan's Rest", which always made me chuckle.
Many or all of the place also feature "double deckers" which are OK. And of course it's facile to disparage a food item one has never eaten. I will say most folks won't like it first time they try it. I didn't. I didn't like eastern Carolina BBQ when I first encountered it in NC either, it looks pretty weird. I enjoy a lot of food items today I probably did not like at first, even cheese, I wouldn't eat it at all when I was young.
When we go back, I do try and visit Blue Ash Chili, which now has moved across the street from the original location.