Granted, I haven't ever had racks from AP, C-Serpents and Reptile Basics, but going by the Boaphile hatchling rack in particular, I believe there is a lot more material, cutting and fitting involved, given that each tub has its own cubby.
To me, quality comes first, customer service is right up there, too. Of course I don't want to pay double for that, but I will pay extra for it.
They all may have similar built quality, I do not know. But I do know that the Rhino Raxx rack has been great for me.
I have a TGR hatchling rack right now, and I do like it. But I want to buy Boaphile hatchling racks in a year or so..