Not sure about other 4wd systems but Audi’s Quattro system is stellar... I would say it might even be the best in the business.... it may not climb over rocks but the Audi S5 we have can get you through just about any bad weather or road conditions with a lot of control. I feel very comfortable that my wife can get anywhere safely that she needs to go during the winter. I just worry about the other vehicles and drivers on the road losing control but not her and the Audi. The Quattro is great!
it really seems to me that there are 2 issues here allwheel drive vs 4 wheel drive, 4 wheel drive being defined as having a low range, all wheel drive only 1 range. I don't know about the audi but for all wheel drive it might be the subaru there is a comaprison test that uses rolllers to isolate wheels and duplicate loss of traction . the toyotas and hondas were pretty much worhtless, Based upon what I know of the sahara i think in mmight do very well. I plead ignornace on the audi. I will say the the oldt toyotas fj 80 with 3 lockers were excellent but had trans problems reportedly