I dont drive a van for a living anymore BUT I have had alot of van driving experience after doing everying from courier to planned routes.
It depends totally on what you want from a van, do you plan to spend time on racking it properly ? Do you want it to carry alot of weight, what kind of size loads ? what kind of distances are you planning (mainly Local or regular Long distances) sounds silly I know but Ive done both , by far the best of the larger vans I have driven was the Older shape Merc Sprinters , very reliable even when loaded up to the roof every day of the week, I am also a fan of the Vauxhall Vivaro / Renault Traffic of the small vans The Transit Connect or if you want the longer internal length the Vauxhall Astravan, these are of course my own views and everyone will have a differant idea or even a bad experience.