My last two vans have been 4motion, I wouldn't go back to 2wd now. I live in rural Scotland and during winter have to tackle some pretty rough roads snow ,a lot of ice etc. I also have to drive a cross fields and farm tracks etc so 4motion is an advantage. 2wd with a good set of winter or all season tyres is very capable though.
I've tried all terrain tyres but took them off after 1000 miles. Great on snow and mud, but on an icy road they were treacherous. Turned my van into a 2 ton ice skate! All seasons for me make the most sense, they work well in all conditions and can more than handle muddy conditions with 4motion and Diff lock.