The "air suspension" on the class C is almost certainly air helper springs, unless it has been highly modified or is a unique chassis. Such air springs can help the handling some and are useful to compensate for the weight that's always on the axle of a class C, but don't expect it to ride like a full air suspension--it won't, by a rather long shot.
On smooth roads, I'd expect either one to be decent enough riding. On rough roads, neither will be exceptional. Both basically amount to truck chassis, at least from a suspension point of view--a live axle, leaf springs, etc.
