Tyres over drivetrain, and the difference is larger than people believe until they try it. A two wheel drive van on proper all-terrains outperforms a four wheel drive on worn road tyres in almost every marginal situation.
The trade is real though: more noise, slightly worse fuel consumption and longer wet braking on tarmac. For a van that spends most of its life on roads, a good all-season with an aggressive tread is often the better compromise than a full all-terrain.