Unibody and body on frame have different pros and cons. Most people buying a truck want a unibody. The F150 lightening is only available in the crew cab version - you can get cars with as much cargo space. If you are actually hauling heavy things, or towing a trailer then a frame is strong and better able to handle that. However if you are only hauling people with some light luggage then a unibody is plenty strong and betters resists twisting forces making for a nicer ride.