I agree on the "Noah" covers. I used them for a few years and they are very well-made. They're custom-fitted for your car, also, which is very important. If the cover doesn't fit well. wind can whip it against the paint and cause scratches.
And regardless of the brand you buy, they probably should be replaced every couple of years, depending on your weather/climate.
Noah is a good cover for the money, IMHO.