I had a Napolean for several years. Cooked really well. Had the infra-red cooking section. When we retired to Florida I gave it to one of our sons. Its still running after 17 years. Be aware, a large section of the bottom rotted out and had to be replaced. The screen over the infra-red cooker disintegrated over time and had to be replaced.
We now have a Weber Genisis. Going on 4 years and love it. Being in Florida, it gets used at least 4 times a week. Excellent cooker. The grill will hold at 350 degrees for cooking the likes of chicken and turkey breasts. Cast iron grates. It grills better than the Napolean.
As to grill covers, I purchased a cheap Char Broil for the Weber. It made it about 4.5 years. I just replaced it with a King Kong cover.
Which ever one you choose, happy grilling!!