We're considering something with a full sized bed as I'll need to handle plywood sheets.
We have a long-bed mid-sized Tacoma and I've hauled plywood sheets in it. You can either put the tailgate down or have the plywood hang out over the side of the bed. You don't need a full-size for that.
Long bed mid-sizes typically are 6'-6.5', and full-size offers 8' beds. We use our truck a lot for hauling everything from furniture, motorcycles, building materials, debris and I've never yearned for the extra 1.5'-2' of bed length a full-size provides.
The benefit is that a mid-size truck is easier to maneuver and park in city traffic - it's as narrow or narrower than most SUVs on the road.
My wife and I are not tall or large people, but if we were bigger-sized then I could see the benefit of the extra leg-room and head-room that a full-size provides. Other than that, I like the space-efficiency of a mid-size.
Full-sized freezer in the bed of a mid-size truck: