I think most covers are all about the same, it's just how much money do you want to part with. Any RV cover will be "breathable" ... they all are. A tarp will not be breathable.
More important, that the "hype" in advertising and how good their product, is if you cover, just make sure it's tied down snug so there is no rubbing against your camper. Rubbing will cause more damage than not covering at all.
If you plan to use your camper over the winter months, covering will become a pain in the neck when you want to uncover. If you plan on using your camper and cover, and you are in a snow region, you probably do not want to cover. When there is snow on top of the cover, it's almost impossible to get the snow off so you can uncover. Then you have this gigantic wet and VERY heavy pillow case to deal with. After using, then putting that heavy, wet cover BACK on is even a bigger pain. So if you plan on using your camper and you live in a snow area, you're really better off NOT covering.
But if you do cover and store, just make sure it's tied down. And by the way, no matter how tight you tie it, you still get some rubbing somewhere.