I have rifles that are cerakoted; Not impressed at all. I'm sure it provides corrosion resistance where applied. However, I had one rifle I was using this Fall that was slung over my shoulder as well as my hunting pack. The zipper on the backpack scratched the coating off of my barrel.
Knowing both will scratch off, I'd go with the cheaper option. If really wanting superior corrosion resistance, I think you have to look at something like salt bath nitriding or Black/Green T. It has to be something that embeds into the steel and isn't a layer. Just my $.02.