As much as I admire the S and its historical significance, every time I've driven a Gen 1 loaner I've cringed at the interior quality and archaic display. If I was going to buy an S it would absolutely have to be a facelift model, probably an uncorked 2018 75D with premium interior option. Would also require MCU2 upgrade and CCS charge port.The S for me is still the best looking and most timeless EV made. Its the car that's got Tesla to where they are now, and even now a 2014 car still matches many brand new EVs for range and performance. Through in the MCU2 retrofit and CCS adaptor, it's still a very very good car.
Full aluminium chassis, air suspension, class leading utility, cheap on going ownership costs, its a car that you can happly own/run for decades. The only reason I can see NOT to get one is the uncertainty around if Tesla will actually sell you a 'new' battery pack versus just a 'refurbished' one when the time comes.
But I still think the 3 is a much better "drivers" car as long as you can live without the hatch back. It's not a small car in its own right either, just smaller than an S. A facelift S feels a little more premium and refined to drive, but the tech feels like the generation behind that it is. Let's be honest a Gen 1 S with the open centre storage "bin", low quality plastic trims, lo-res display and crap seats doesn't cut it against any of the newer Tesla options.