Having been around both, I like them both. They are different, for the 124 is a quantum leap ahead of the 123. The 123 is a very capable sedan for its time. I believe it has incredible dynamics in handling and braking. All around a nice car to drive in most conditions. The 124 is much better in terms of outright performance. In fact, its a little known fact that when the 124 came out, they paced it against the legendary w196 Mercedes racer and the w124 could keep up or beat it on a closed track! Very impressive. I also contest that the following w210 was not quite the step forward as the 124 was. It had quality issues, and hardware wise, lost the magic of a Mercedes to some degree.