I've had all three - Good Sam's, Coach Net and CAA (
Canadian Automobile Association). There are advantages and disadvantages to all of them.
Good Sam was the sketchiest for me. At the time (about 4 years ago), there were unanswered questions about what they would cover (and dollar limits) outside the lower-48. Some of their literature said $1500/yr, while their call centre said there were no limits - it was frustrating and I never did get a clear answer. What I disliked the most was they would tow only to the nearest approved facility. Not to my dealership, not to my driveway (assuming, of course, that I was a reasonable distance away from either). That said, I only used them once (keys locked in vehicle) and it was a good experience.
CoachNet is definitely focused on RVs - and specifically coaches. Coverage includes family members (who live with you). They have help lines where you can find campgrounds and reliable service depots and RV information lines staffed by licensed RV technicians; CoachNet is about far more than roadside - they're about the whole RV ownership experience. I liked them, but I really don't need/use the level of hand-holding they offer.
CAA (specifically, CAA RV+) is my favourite. They're the only one who also covered any vehicle I may be driving, including my motorcycle. They offer two-tow-truck extraction if necessary. And they tow to anywhere I want (within 400km). I see vehicles with member stickers all the time, and I see tow trucks from their affiliates all the time; both give me some confidence that they're trusted and will be around when I need them. Apart from various hotel/motel discounts and attraction ticket discounts, I also get a 20% discount on my RV insurance through them; they even had the best price for plane tickets to Orlando. Over the years, I've used them for key lock-outs (many, many times), for flatbed motorcycle towing (several times), changing a flat tire (it was on a 8-lane highway, it was raining, and I was in a suit), battery boosts, pulling my trailer out of a mud pit, and so on. They cost about $20 more than I'd like to pay... and that's why I tried out the other two providers... but, I've always been happy with their service, so I came back to them.