Our local sailmaker makes Laser covers that last for years in the sun and seem to be mold/rot resistant. www.bartlettsails.com The covers don't stand up well to travel...but for boat yard covers, I can't imagine anything better.
Send a PM to user 48111 on this board - he makes some really good covers at great prices. I've been using his now going on 5 years and they are holding up great.
If you want an inexpensive cover... check out www.intensitysails.com. I have a full boat cover for one of my boats and it does a good job. Nice inexpensive way to pamper your boat
If money is not an issue and you want a really REALLY nice set of covers check ot http://www.sailorstailor.com/. When I grow up and have money this is where I'm going to get my boat covers
I have a colie cover and they will personalize the covers too mine says "Jack's Laser" there very durable and they have a hole on the bow so you can tie a rope on it while the covers on or while your travelling. There great covers
I live in Florida and my boat sits outside under a cover all year round. Half is under a tree and half is in the sun.
My Colie Sails cover is holding up beautifully! I had a cheaper one but it lasted less than a year before showing serious flaws. If your environment is harsh I would highly recommend the Colie covers. They are expensive (which is why I tried the cheaper one 1st), but worth every penny (IMO)
Kinder Industries makes a nice cover also. Pricing is a little better than colie. Plus, you can pick any color that top-gun comes in. I went all crazy and bought gray.
I have a set of Colie covers. They are 4 years old (have spent a lot of time in the garage) and handle interstate driving quite well. Definitely a good cover.
I made a minor modification to the hull cover - I sewed a piece of indoor/outdoor carpet (the same that is on the bunks of the trailer) to the cover where the trailer tie down straps cross. I was concerned the cover was rough, and might abrade the hull under the straps on a long road trip.