the sprinter is one of the best out their, they are everywhere, anywhere you go you'll see the sprinter. even some very high mileage sprinters that look and drive like new.There are so other work vans. The Sprinter is the one that I hear talked about most. It is more expensive, but it is quite popular. I'm sure the Benz label comes with some added comfort and amenities.
This review of the Promaster is great though. I like the guys at TFL. I think they give a pretty fair assessment of most vehicles and their reviews aren't terribly boring either.