My boat stays in a portable garage so the only thing I use a cover for @ this point is to keep dust and dirt out of it when it's not being used.
Have been using a cheap ebay purchase for close to 10 years, but it never gets exposed to the elements.
I don't trailer with it because it wouldn't last a season.
If I needed one for trailering and or it's exposed to the elements 24/7 I would purchase a custom for it.