When Kennon came out with their "sunbbrella" covers, I ordered a set of wing covers from them.. UV is the biggest enemy of covers. Those went through two seasons, then essentially fell apart......UV deterioration. I called them and they said the covers were no longer under warranty....too old. Haven't bought anything from Kennon since. Hopefully, they've got their materials figured out now, but I wouldn't trust their customer service.
I second using Alaska Wing Covers or Aviation Covers...both make good stuff, and back their products.
I'm a firm believer in NO monster engine covers. I want minimalist insulation in engine covers.....and stuffability. Those monster covers from WIGGYS are a waste in my experience. Try sleeping in one sometime

. You'll regret it if it's cold. You need to carry survival (or camping) sleeping bags in any case. A RELATIVELY thin, pack able engine cover is the ideal.
Finally, let's say you get stuck out somewhere in weather, and need to spend the night to wait on weather.....next morning should be fine WX. Now, you have your "sleeping bag/engine cover". Are you going to use it to sleep in, and turn this into an actual emergency because your engine won't start in the AM? Or the alternative?
That engine covers not going to hold heat all night, no matter how thick it is....in real cool WX. You're going to have to get up and run the engine a couple times that night with a cover.....but if you're bundled up in that cover, you'll be up all night running the engine. I've been in this situation.
Good compact covers and compression stuff sacks can get both sleeping bags and thinner engine covers down to reasonable sizes.
MTV