I don't know about costs of running either alternative type. But, in past motor homes (about 8 of them) we had no issues when used on propane. Cooled as well as any other.
Two days ago I did buy a used frig, with inside freezer box. While these work ok, I wasn't after freezer. This was great shape, good price and is for milk and eggs! When I open frig & see wall to wall milk.....well, it came to mind that I needed to reclaim my frig!! Soon I will be milking 3 does. It happened at perfect time.
I've been looking for a while.

I off the breaker on my hot water a day at a time and that will more than pay for this frig elec use....small unit, about 5' tall.