Right now, I have both. A 28' Class C (no slides) and a 28' 5er with a superslide.
For sightseeing and all-day drives, nothing beats a motorhome. We pull into an RV park, throw out a couple of cords, and we're done for the night. "Potty stops" don't require getting out of the vehicle. While stuck in a traffic jam, you can fix snacks/beverages/watch TV, etc. BUT - after spending a month living in it on our trip to Alaska and back - we decided it might be a bit cramped...LOL! The "C" also doubles as our trailer tow vehicle and "home" when Ed drag races; and pulls my kayak trailer when I do camping/paddling weekends with my kayak pals.
So we're planning on trying a bit of Snowbirding, and bought a used 28' 5er. We'll spend 5-7 days each, parked in a few different locations. When the slide is out - it feels like an "apartment" inside...LOL! A LOT more work to set up and take down.
Beds: both of ours have raised areas near the beds, so either RV offers easy entry.
Steps: the 5er has more steps to climb
Cargo Storage: our Class C has more "basement" storage; the 5er has massive storage inside.
MPG: not sure about this - I think it's going to be a "wash"? The "C"/E-450 gets around 8-8.5 mpg using gas (cheaper) and didn't seem to care if we were pulling a toad or not. The non-towing F-350 can get 22 mpg on the highway! - BUT - it's diesel (more expensive) and we're stuck using 22' of truck as our "car" once we're parked, so parking could still be an issue. Not sure of the mpg while towing yet. I suspect that at the end of our trip, our total fuel money spent will be about the same?
Driving: Our Class C has been an awesome vehicle to drive. I hope the truck/5er handle as well? There's really not much difference in length between a 5er hooked to a long truck, or a "C" pulling a short toad. Both require some planning regarding fuel stops and how you can exit again.
I'm looking in my crystal ball at our RVing future: I ultimately see a "Super C" with a couple of slideouts.....LOL! But before we invest that kind of money - we want to make sure we can sit still for that long ;-)