Speaking only for the cab, the Sprinter offers the most space by a wide margin, and the chevy is better than the ford by a small margin. Another big factor, is when you test out the driver position, make sure the slideout is in. When I was shopping, the slideout in every single ford and chevy chassis rig restricted driver seat movement and I couldn't move the seat back far enough for myself, even at a short 6'0". The sprinter carries its own set of issues. If nothing mechanical goes wrong it's great. When something goes wrong, service is more expensive and harder to find. I do like getting 16 mpg with the sprinter, knowing full well I'll never break even with the extra upfront chassis cost. Like almost everything else, it's all a big pile of priorities and compromises.