We have Good Sams because we camp frequently at a Good Sams Park as our hotel room near where our handicapped son lives. Because of this, the membership pays for itself every year. Otherwise, we probably wouldn't have it, b/c we tend to camp in state/federal campgrounds for pleasure. We don't use Pilot/Flying J as much as the name brand stations (Shell, BP, etc.) so we can get gas with the extra additives in it.
We buy things occasionally at Camping World, but their prices are high, IMO, even with the discount. We wait for sales.
If you get a membership to any of the mentioned camping discount organizations, be sure that you'd use it enough to be worth the membership cost.