tech changes like the battery and pump can always be implemented later on with the X, as they have started with the latest battery and motor tech. it's just a matter of time before the X catches up with those upgrades, and when it does, it'll come down to personal preferences and which features you prioritize between the two, AKA which design you like better.
i went from a 2018 M3P- to a 2016 MXP90DL+ which i think is a jump in design features (although older tech). here is my break down on why i made the switch
X is better:
- "phone as key" on 3/Y is only good if it works. sadly this was hit or miss for me (and many others), whereas the fob works 100% of the time
- better storage cubby cover than the flappy center console storage on 3, which was picky about closing plus you needed to fold down in a certain order
- falcon wing doors
- christmas light show
- automated close/open ALL doors. easy operation from fob or center screen. not confusing or ambiguous door popper button
- screen behind steering wheel gives more instant and direct details
- more steering wheel buttons for quick and easy adjustments
- steering wheel column more traditional for easier adaptation
- manual adjustable A/C vents for quick adjustments
- adjustable suspension
- adaptive headlights
- unlimited supercharging (although i did have this on my 3)
- dual charger upgrade for 72A home charging
- ventilated seats for heating AND cooling
- bio weapon defense mode
3/Y is better:
- front cupholders better at the bottom than on armrest, allows storage inside armrest
- quieter, no warm up for performance (i hate waiting for the X to heat up for Ludicrous+ mode, plus it's loud; battery fan?)
- back seat fold down controls in trunk
- more options in folding down the back seat
- roof rack capable
- simplified dash makes cleaning easier
faster supercharging for newer tech relies on everything being in tip top shape. i can't remember the last SC that charged at the rated speed (i most always have to do the charger shuffle to get an acceptable rate). the better heat pump is awesome if you're in an area that could benefit from it. more efficient motor and battery improves all the time but I have unlimited supercharging so NBD, i just have to charge more often. phantom drain is my biggest complaint for all their vehicles.
The X is a great car and I have loved driving it the last 2.5 years. However, Tesla has clearly not spent significant time updating the X due to Model 3 and Y production. If you need a usable third row, then absolutely get the X, but the Y is a great option for the money. When the X gets a new battery pack and interior update, then it will be the better option.
Addressing some of your items:
-FWD have their advantages, but there are negatives. Largely the attention they draw.
-Automated doors is a feature I turned off, as the door will open when I don't want it to.
-Phone as key - buy the fob
-Dual charger - not available on current MX cars.
-Xmas show - Not a functional feature. I did this when I first got the car a few times. Haven't done it since.
-Headlights - The headlights on the 3 (presume Y) are supposed to be far superior than the S and X. See ratings by NHSTA and IIHS.
Here is my list for Model Y - Updated battery pack design (2170), more efficient 121 MPGe vs. 90 MPGe (20" Perfs), 250kw Supercharging, heat pump (this is big for northern states/colder climates), Model Y has more leg room in front and rear than MX, updated interior/landscape screen format.