Traction in slippery conditions is no contest between our '90 Accord and '91 190E. The Honda, driven carefully, will go through almost anything if it won't bottom out. The Merc likes it bone dry, no traction control, etc. On the other hand, our 5 ton RWD m'home with 4 of those on the big-lug duallies in the back can motor figure-8's around either on ice or through the fluffy - or most anything else on the road, regardless of drive geometry.
My late '88 Integra could out-handle either on a twisty, uneven road, and inspired confidence driven fast. Still, both FWD's had noticeable understeer under all conditions, and feel less nimble in tight turns than the 190E. Both bottom at the nose entering parking lots, and at times require 3-point maneuvers to park once in. The Merc has no problem.
Bottom line, though - I wouldn't make a decision on any car based on drive geometry - good choices come in both flavors for almost any criteria - as do bad. I wouldn't own a Benz because it is RWD. I would because it is a Benz.