I’d be inclined to leave it uncovered.
Loose covers can chafe paintwork if not secured firmly and if not permeable to moisture getting out can cause all sorts of paintwork horrors if left to fester over the winter months.
In my view the drawbacks outweigh the benefits when using covers on cars left outside for long periods.

 

Buy a cheap gazebo to put up over it 😁. Not sure on car covers but have heard they need to be breathable.

 

If your issue is hood-related, there are covers available that only cover the top part of the car. No use in a garage for keeping dust off, but might help keep the water out without the risk to the paintwork.

 

Hi, we bought a "cheap" cover for the our car & it lasted 9 months & was a waste of money. Replaced it with this, Audi TT 2000-2006 Cabrio Shield® Premium Soft Top Protection & it is still going strong 4 years later. Our car sits outside all year round & using the cover has caused no issues at all. In the colder months I do put a dehumidifier pillow in the car to help keep the moisture content down.

 

The halfords ones are good and only £70