It sounds like this is too late for the OP, but for others deciding: we have an X and a 3.
For day-to-day driving, I far prefer the 3. 1500lbs lighter - smaller, easier to park, far more efficient, it depreciates less, and has much more pleasant handling. I take it whenever I can.
But, man, there are a lot of times when that X comes in handy. The frunk is way bigger and easier to get in to. The higher roofline and doors make it a lot easier for our limited-mobility parents to get in and out - and, I can open and close the door for them from the inside. And of course it has a ton more cargo space - and that big, powered hatch makes it easier to get to. It comes with a hitch (though you can add one to a 3). I think it's more comfortable, although that is obviously subjective. It also has a fob, which comes in handy for opening doors and using summon, and works all the time for passive entry (unlike my phone with the 3, which only works about 80% of the time). I also like having two screens, as you can display more data at once. When driving to a trailhead, the adjustable suspension is nice. When out driving for pleasure, the extra view through the large windshield enhances the experience.
Both have similar Supercharging schemes these days. The stereo systems seem pretty comparable (but try them; they are different). Autopilot does pretty much the same thing in each. Phone app access is about the same.
I really like having both, and being able to pick the best tool for the job. If I could only have one Tesla...I'd have a Model S. Most of the cargo space and accessibility of the X, while being somewhat more efficient and not quite as ponderous to drive (though still more of a boat than the 3). (Before the X and 3, we had two Model S, and put over 100k on them. Great cars. Also the best-looking of the bunch IMO).
As for the OP's more-current concern about how to buy an X: definitely look around for used ones...but I was very disappointed when I looked. There were very few available, and they were very little less than buying a new one. Inventory, as RedMS mentioned, is another good idea to try - I got a fantastic deal on an S that way once - but there are usually not many of them in inventory, either. I ended up buying a new one.