I use an ADCO cover. Do they help? Consider inside storage, price it out, then consider outside but under cover storage, price it out.
At that point, consider covers and look at it working for you for two years. Compare that to under cover. Best solution might be to put a full length tarp over your cover. Tarps are cheap but work for a year or two and add to the life of what is underneath... the cover...
Best of all, cover your sharp edges on your rig before you put the cover on. Make sure your rig is really sealed well because water will find it's way in if it finds a bad seal no matter what cover you have.
Mike
2012 Winnebago Impulse Silver 26QP
2005 16.6 Double Eagle
2018 Jeep Wrangler JK
previously Snowbird Campers,
Triple E Motorhome and Fifth Wheel