You'll get the most consistent car by using both, setup station then
camber gauge. The setup station is the only way to set toe accurately, and also gets you in the ballpark for camber. Then once you have your tyres mounted up do the final check with the camber gauge.
As people have mentioned, wheels and tyres can be warped, bent, wobble, etc. The best thing to do is to take 3 or so readings with the gauge and make sure the average is what you want your final camber to be. This is how Jilles Groskamp does it as seen in his pro-tips video