As someone who has been ping-ponging back and forth between our S85D and 3LR almost daily for five months ...
My initial feeling was 3, all the way.
It's now much more 50-50, or even leaning slightly S ... until one compares price. The fair comparison will be 3LRD at $60-65K loaded and an S100D at $110-115K loaded. (Each will be at roughly 340 EPA range test miles). Consider cost, and it becomes a little tougher to justify the S.
Only justifications I've come up with:
The fun factor of having one of each does go way up. Each day, one looks forward to the fun of driving a new car. (One needs to have a like-minded spouse for this. In my case, it was actually her idea.)
It is useful to have one vehicle with massive road trip capabilities. Our S has swallowed furniture, assorted recreational equipment, and several small northeastern states.
So, why leaning now 55-45 in favor of the S, though? Mainly the display(s). The dash display is the least of it. Nice, perhaps. But the speed is easily blocked by the wheel. And, the new nav is nice ... but nicer when shown on the M3's center display.
No, the problem is with the center display itself. Super nice. Super sharp. But small. And landscape (in order to optimize phone charging, I guess). I've realized that I prefer the larger portrait map display on my S, even though it's the less-sharp-and-vibrant MCU 1 version. A portrait version of the M3 display would have been a home run. Something I'd use far more often than front-and-center phone charging.
More importantly, the 3's display is not canted towards the driver. And, the map is shoved towards the harder-to-view far side, all in order to leave plenty of room for ... um ... a giant empty white space ... which contains an Autopilot car display which only rarely shows much info of real use and interest. (Suggestion: Slide the map all the way left. Leave the speedo where it is, against a blurred-out map corner, joined by other useful info ... including time and temp, which are currently off in the northeast Siberia corner of the display. And, put the toy-car display, narrowed, on the far side. It's big enough that all key info would still be visible.)
Beyond that, the S does have modest, yet meaningful edges of looks and road noise, with a more modest edge in ride smoothness.
If a fully-optioned were $90-$95K ... and not approaching a probable significant refresh, it would be an easy call to upgrade 85D to 100D, to enjoy alongside our 3LR (which we'll probably upgrade to D).
As it is, our choice is 3LR + 3LRD vs. 3LRD + S85D. Leaning towards the second, but it seems a bit silly to keep a "great road trip car" that has significantly shorter range, earlier Supercharger taper, and slower per-mile Supercharging.
