Most folks tend to like what they have. Had this post originated in the C Forum the responses probably would be overwhelmingly in favor of C's vs what we are seeing here. Posted in General RV'ing would more likely get you a more balanced response. i have a small (24') C but have spent some time in and alongside a 40' DP.
The one issue the A folks simply do not talk about is safety as the C's win that one hands down. The A's do not have air bags and this for me at least, is a huge issue. That big windshield in the A's comes with several problems, it lets in a lot of heat and light that is not always easy to mitigate and god help you in a front end collision.
Serviceability gives a nod to the C's as well as virtually any Ford dealer can work on the E-350's/450's while A's require a higher level of specialization. It usually comes down to a floorpan you can best live with followed by storage and towing capabilities. C's are easier to drive and park, A's haul and stow more stuff.... the choices are endless. Good luck!
:C