We have had a 2006 Sprinter B outfitted by Sportsmobile that we sold after 110,000 miles and currently have a 2014 Mercedes Sprinter outfitted by Advanced RV. We liked both of them for different reasons. The 2006 was fairly inexpensive by B standards, required little maintenance, and did the job. The settee/bunk arrangement and slide-out pantry were excellent.
The current B is so classy I can hardly stand it. It has the "magic batteries" discussed above that provide 600 amp-hours of 12V power. It does not have propane because I had 2 serious propane leaks with the old van.
I would suggest going to RV shows, or talking to people at campgrounds about their vehicles and what they dislike. Sit back and review whether those things appeal to you.