I agree with the advantages of the E series for appropriately sized class C motorhomes. Serviceablity, safety, etc.
But overall for me, class C (on typical chassis) RVs are best for units less than 29 ft. Once you hit 30 ft, the C and the A start to overlap in size and many Cs are very limited in weight carrying ability.
I know this grossly oversimplifies things but 27 or 28 ft and under the C is at it's prime. If it is 30 ft and over start seriously considering a class A.
I'd say the first thing to consider is how big do you want?