If you plan to get a M3P or MYP, I'd try to hold out until the later half of the year if you're not in a rush. Both models will have upcoming updates.
M3P: The CAT3 3D6 Hairpin DU (rear) and LG 5L battery should be on their way. The 3D6 DU paired with the LG battery will produce an extra 16kW over the current model (like the MYP). The LG battery should provide more power over a broader range of conditions (SoC & temperature). This should result in less power reduction when the battery is cold and at lower SoC.
Of course, we can dream for a Model 3 "Plaid" edition with some of the Plaid's new tech.. redesigned rotor armature design (inline star laminates & end-caps), stronger magnets (~35%), upgraded stator/inverter, increased cooling, drag mode, etc. and eventually the 4680 cells, structural battery pack, and megacasting.
The MYPs from Austin will of course have the 4680 structural battery pack and megacastings. There's no question as to if this is happening, just how will one go about ordering a MY from Austin rather than Fremont.. and how much more will it cost? The structural battery pack and megacastings should allow the MYP to drop to around the M3P's curb weight while having the potential to produce more power and increase range depending on the battery capacity. That is if Tesla doesn't handicap it via software limits.
The MYP makes more logical sense as it'll be the better car. I expect that it'll have better build quality, be lighter, more powerful, increased structural rigidity, potentially more range.. and of course increased cargo capacity compared to the Model 3. It'll be better engineering, more practical and more efficient.
I think it'll be a while before the Model 3 gets any major upgrades since the focus seems to be on updates to the MYP & then probably the Cybertruck. Then there's still the Roadster..