I've owned and driven both cars, I had a 1997 Taurus SHO that was about as reliable as a Yugo, but then again it could have just been that car. Little crap would break all the time on it that would end up setting you back pretty damn far in the end. As far as the Contour, it's not really pushed to much but the tranny started having problems around 67k and had to be repaired (I forget exactly what was wrong with it) and had a fuel pump problem but other then that very fun car. Like everyone else has pointed out if you even THINK about getting a 96-99 SHO make SURE that the cams have been welded, the last thing you want is to purchase it and drive it for a week only for it to be destroyed.
A good site for the V8 SHO's is V8SHO it has everything you'd ever want to know.