I sold my 2016 Golf R around the same time we picked up the 3. I actually was pleasantly surprised by the quality of the 3, to be honest. Maybe my expectations were low-ish because I spend a fair bit of time in a Model S, but I really thought they did a good job of stepping up and making the interior relatively premium. Where cars like the R feel 'premium' to me is how they glow at night. The interior just felt REALLY high end, better than a base BMW, all the glowing buttons and stuff. But the Tesla just doesn't HAVE the buttons. To me, that's different, not worse.
The nav/display is obviously better in the Tesla (although my Golf didn't have the digital cockpit that they're putting in the new ones). Both cars have their 'fancy' seating material (leather/fake leather/whatever) on the seating surfaces only, cloth elsewhere (and, by the way, I hate leather seats, I just want cloth in everything.. I'm just saying, this is one way premium cars are differentiated, is by FULL leather). The most galling thing to me on the R, the only real sign of cost cutting, was the manual passenger seat, where the 3 has a power seat. A low end touch on both is the totally spartan, stripped out finishing of the trunk/hatch area.
No swiveling headlights on the 3, but the headlights are actually better, significantly so, particularly on high beam.
Perhaps one thing that keeps me from being as critical of the 3 is that it's an appliance to me. I'm a german car fan, and I hate sedans. My BMWs and VWs have been cars I'm passionate about. The Tesla just takes me from Point A to Point B. And it's a fantastic car. But maybe that makes my expectations lower.