That's very difficult to say one way or the other without knowing more about the local dealer. If they have been in business for a long time, have a stellar reputation, well kept lot and bays, attention to detail (which is easy to tell when you do a walk-through and see how much you can find that needs attention OR how well it was prepped prior to showing), a wide range of services with on staff tech's, etc. you might get a more personal touch and quicker turn around. With the caveat that dealers are notorious for being your best friend until you drive off the lot. If it's practical, try doing a drive by for a few days in a row. Are the rigs in line for service turning over or is it the same rigs in the same place every day.
On the flip side.. Camping World. Service may be more standardized, but not as "invested" in individual customer satisfaction. They know that in most cases.. once the rig is "repaired" you're on your way down the road and you just became someone else's problem. It's easier to get "lost in the shuffle" and processing things like warranty repair authorization may take longer. However, you probably have more recourse with CW if you are not satisfied. Any parts you might need are probably more likely to be in-stock or within a stones throw away.
As far as being a national company... I wouldn't weigh it all "that" heavily. What are the odds that you will break down within 200 miles of the next CW?
I might just be jaded though. The few times I've needed a repair it's always 50 miles to the next little town with a population of 2000, 1 repair shop in town, everything closes at 5, and it's 5:15 on a Friday night.
Definite +'s and -'s either way. Visit both.. pay attention to their service bays and overall attitude of their employees.
Then... go with your gut!
I would say though that the greatest priority would be in choosing the rig that best fits your needs/wants. After all.. you're not planning on camping in a service bay, right.