You can search around for information regarding cost of ownership on most of these brands and engines. Mercedes definitely seems to be towards the top, if not the king of this category, and that is not even considering the fact that mercedes diesel sprinter mechanics are fewer and farther between. Ford, Chevy and Dodge are going to be cheaper to maintain, period.
In many cases though, that's not enough to sway a buyer. Sometimes the body/size/price and configuration just are not available without the sprinter. The three mentioned above are only available in traditional "van" styles, or class C's. The new Ram is a bit lighter weight than the others (no slides, less towing). Of course, you're always gonna find a few MB owners who swear by them, have driven 800000 miles without trouble, etc..
This says allot: