Many like KOA's because they know they are going to get a decent place cost is secondary. I have overnighted at a dump or 2 simply because plans changed and I needed a CG on short notice close by.
KOA's maybe pricey but they are generally NOT fish camps. With the KOA brand you are generally assured a decent(not superior) site. Knowing there is a standard to be met. Many are comfortable with the KOA brand. At some point it becomes more about finding a reputable place to stay vs. an economical price. Pick your poison. Do you want a worthwhile place or do you want the lowest price.
KOA is not my favorite place and generally not my first choice however I have not stayed at a bad KOA.
KOA does ensure a quality standard that supersedes price for many. KOA's are also very different and are independently owned.
If in an unfamiliar area I might lean towards a KOA vs. Joe's campground especially if I'm staying for more than just an over night.