6 wheels good, on two axles, rear wheel drive.
6 wheels bad, on three axles, front wheel drive.
Reasons, with 3 axle FWD you will suffer from poor traction, espescially when you're trying to turn at the same time because the 2 rear ales are trying to go straight on.
Second reason, tyre scrub. That's why trucks can lift axles on te tractor unit and trailer.
If you never go off road or encounter slopes or tight bends then the 3 axle vans should be O.K. otherwise if you need the capacity that 6 wheels gives then 2 axles RWD is the way to go.
Got to admit the tag axle vans do look the dog's though.