Definitely a personal question and there isn't a right or wrong answer. With that said there is a huge difference in used Model S cars since they range from 2012-2020. 8 years is a lot of changes and there used to be a much wider range of options you could get vs today's choices. But I agree with what was posted above about
price being the #1 concern.
I have a 2016 90D (UHFS, air suspension) and have drove a few loaners that were slightly older 2014 and 2015 and they drove/felt completely different than mine and would have been disappointed if mine drove and rattled like the loaners that I had.
- 2012-2016 I would try to go 3rd party and drive the car before buying it since the cars can vary so much. (there isnt much benefit buy directly through Tesla now that they dont have a CPO program and greatly reduced their warranty from 4yr50k miles to 1yr10k miles)
- 2017-18 is kinda in the middle with most options being streamlined but the middle display screen computer (MCU - Media Control Unit) getting upgraded halfway through the 2018 year to the MUCH snappier MCU2
- 2019 or newer there is much less to be concerned about since the car's options are much more limited.