3 link vs triangulated 4 link - Why is one better?

[Tinker]

To do a proper 3 link you need more room for the upper link. Triangulated 4 links are good when there are space constraints. The shorter the upper links are( triangulated 4 link), the more your rear axle will "roll" and change pinion angle. The more travel, the worse this gets. An upper link closer in length to the lower links minimizes pinion angle change, but say goodbye to a back seat in an oem car.

Not only does the axle roll, but it will also somewhat induce rear steer in the axle housing in turning situations. One side of the car goes up, and one side goes down, shortening the wheelbase on one side, and lengthening the wheelbase on the other thus inducing rear steer. Properly engineered and adjusted systems will minimize these effects, but they still exist to some degree. The 3 link with panhard bar or watts link also is very simple to adjust rear roll center height. Are you racing it? Will you be tweaking on it during track days or autocross?

Just my .02.