Which Class C Should we buy and why?

For probably less than the cost of a trailer to haul your car behind you, you can get a base plate and tow bar setup installed, electrical for lights, and a supplemental braking system. You just have to make sure the vehicle to be towed can be towed with all wheels on the road. Then you don't have to worry about tongue weight limitations with the motorhome, or what to do with an extra trailer when you get to your destination. A car dolly that carries only two of the towed vehicles wheels and lets the other two roll might also keep things under the tongue weight limits, but you still have to put the dolly somewhere when your camping.

(Drew beat me to this, can't figure out how to delete mine lol)