Me and several prairie dog shooting friends have a bunch of those Simmons 6x-20x 44mag scopes and have been happy with them. The newer ones with the side parallax adjustment don't seem to be quite as good. However, at 100 bucks a pop from Natchez they still work fine too, even when cranked up to 20 power and looking at a prairie dog 300 to 500 yards away. I think they are the best bang for the buck, and decent glass.
I'd say between me and my friends we have over a dozen of them and have never had a problem, using them hard on the prairie for more than 15 years. As far as accuracy goes, they are as accurate as any scope. Most of our rifles are shooting 1/2-inch groups at 100 yards with these scopes on them.