While not "Truism's" here are my thoughts.
1) Class A's have larger tank sizes.
2) Class A's have more storage capacities
3) Class A's have a better view from the front seats while driving and while parked thus giving a better feeling of space.
4) Class A's look better except for the streamlined C's that some call a B+.
5) Class A's make better use of the driver area seats while parked.
6) Class C's have better sleeping options for families.
7) Class C's are easier to get out of at fuel stops
Both can have auto levelers, both have a learning curve when backing up, and are about the same to setup once you are in your spot.
Good luck in your decision process.