Even with a conventional 4WD (Jeep Wrangler) I still prefer to have them on the front. Reason is that the front wheels are your steering wheels, going up or down the hill. If you get into an oversteer type skid (i.e the rear end loses control) then you still have steering and should hopefully be able to steer your way through it, (or if really desperate put it in the ditch on the upslope side of the road rather than going for a tumble down the hill). Most modern AWD vehicles with traction/stability control and ABS usually are orientated towards front wheel understeer rather than rear wheel oversteer, and as other posters have mentioned, are also usually orientated towards driving the front axle only in most situations.
I have memories of descending a nasty little switch backed gravel road leading to club ski field in New Zealand in a Delica van with chains on the rear tyres only. We had no grip at all on the front axle, which tended to follow the fall line of the road, eventually sliding into a ditch, luckily on the upslope side. Waited hours for a snowcat to yank us out.
The only exception I could think of is if you were in a pickup with a trailer or heavy load in the bed over the rear axle.