Something to think about with a car cover outside. If the car has dust or light dirt and the wind is blowing the cover around you will be scratching the paint with the movement of the cover. I don't know which is worse, the elements or the cover.
There's really no cover that's an answer to all prayers.
I've lived for the past 3 years without a garage (I won't go into the tradeoffs one has to make with urban housing and proximity/drive times, I could own a giant house with a fabulous garage but I'd have a 1.5 hour drive each way every day. I chose to live close and commute less, but the cost of housing goes up exponentially and affording a home with a garage and no commute is in the $M's.)
Anyway, I've become quite the expert on protecting my Shelby.
1) Cover has to fit snugly to avoid mechanical rubbing. Wind action is unrelenting and even a 10 mph wind can rub the finish off a car if the cover isn't soft/plush and snug fitting.
2) Most covers choose to "breath" because they try to avoid situations where water and moisture collect under the cover and mold. I've found this to be a very secondary and obscure consideration for reasons I'll outline below
3) I purchased a Cover King cover with microfiber lining that's very kind to the paint job and fits perfectly, has elastic sections where it needs to be a very snug fit. However, because the cover isn't completely waterproof, the water weeps through the cover and over time, I get residue on my car from the fibers coming off (like a fine white powder).
A buddy of mine with similar situation and no garage elected to "camp dry" his cover and it repels water and is essentially waterproof. This prevents suspended dust/dirt in the rain water from ever getting through and coating the car in a fine precipitate.
After a hard rain where the cover becomes like a wet t-shirt on the car, the soaked water leaves a very fine dusting, especially in the areas of the hood and the rear deck where the water pools while drying up.
At the end of the day, for exterior protection I recommend a very tight/snug fitting, no "liner" or fiber soft/plush material that will eventually separate and whatever cover you get, buy some waterproofing spray applied coating (like for camping gear). If you remove the cover often enough, mold is not a concern.