MX starts at £83k in the UK for the basic model long range model, in white with 5 seats. Start adding a bit of colour, change the wheels, add a seat or 2 and you're at £90k+.
It does have a better range, performance and that charging network. Its arguably quite a practical car for families (but can't take a roof box). Over the air updates...
There are drawbacks; whilst those amazing doors are handy in some situations, there are plenty of reviewers complaining they let in water when opening after the car has gotten wet. They malfunction regularly, are very sensitive and a pain to live with. You also have the Tesla build quality, which some folks consider to be lacking. Most folks agree at least, isn't in Audi's league.
The e-tron can be had for significantly less money in a variety of configurations. Like you say its a more luxurious car and the build quality is excellent, handling is better. Its just as family friendly, with lots of cargo space, options for roof box if required (both have towing capability so yes, towbar mounted box is an option on both too). Not as quick as the MX and doesn't have the range the MX has, nor the charging infrastructure at the moment (which will be a moot point in the coming year or 2).
Personally... if money was no object I'd still go for the e-tron. The Audi meets my needs in terms of handling, practicality, build quality and range is acceptable. I would rarely need the faster 0-60 time or additional range.
I have a model 3, and generally would prefer the e-tron (SUV!). That said, charging infrastructure is crucial if you want to take it on long trips. Tesla in the US is very built out. For EA, it depends more on where you live.
The fit and finish of the Audi can't be denied. I garage my etron and have a 240 V charger, and find in my weekly routine I only need to charge up every 6 days, or so. Ultimately, is serves me extremely well for 90%+ of my driving. I haven't tried any extended trips yet. Frankly, from what I have read about the fit and finish of the MX (JD Power puts Tesla so far down on its fit and finish list that the company forms a category all its own), it would drive me nuts in my daily life. I actually look forward to getting into the etron because it is so comfortable and fun to drive in the real world.
I have a 2020 Tesla Model X and a 2019 e-tron. I really like both cars, however, they both have their positives and negatives. If the Audi had the network of charging stations in the US and the same range as the Tesla, I would go with the Audi as my top choice, but that's not the reality. Here are my thoughts on rating both cars on positives and negatives:
short learning curve to get up to speed; very similar to my previous ICE Q7.
build quality is excellent and design is very functional
Excellent seats, visibility and handling.
Nice balance of traditional controls and touch screen interface
Very quiet and excellent acceleration
Cost is a bit high, but with current US discounts and incentives, a decent value
+Audi has a professional service organization
Range limitations for longer trips
Charging infrastructure is lacking in the areas i travel
-The Audi connect App and and other tech features needs improvement
- a bit tight getting into the car for someone 6'-3"
TESLA MODEL X
long range, and seamless charging infrastructure in the locations I travel.
If you love technology, this car keeps giving you new things to learn and appreciate.
Over the air software updates are the only way to go (hello Audi)
Good visibility and handling.
Mostly quiet unless at high speeds and exceptional acceleration
Excellent standard cruise control system
+Top safety crash ratings
+ You definitely feel like you're driving cutting edge technology if that's something you value.
No front facing cameras or 360 view for parking - are you kidding me?
Many functions are on the touch screen and the icons are way too small for such a large screen. Hard to make adjustments while driving, almost need a co-pilot.
-Expensive and no negotiations
-Build quality is lacking in several areas.
-There is a learning curve to get competent with all the functions and controls. My analogy is it's like going from a flip phone to a smart phone.
-Tesla is still trying to figure out how to run a service department, needs improvement
-"Vegan seats" don't seem to breathe well and get hot with no cooling seats option.
-The all glass dome roof is NOT cool in a hot climate. Clearly this car was designed by people living in the very moderate SF Bay Area climate!