I bought my wife a standard P365 because she wanted a small automatic for pocket carry plus she could work the slide without issue. I liked it enough I bought another one for me. On my own I would have preferred the XL for the 3.7" barrel but I wanted both pistols exactly alike for the same user interface, magazine compatibility, etc.
We probably have 500 rounds thru the pistols so far without any stoppages. That's a mix of any kind/brand/weight of ammunition I could find during the Last Great Ammo Shortage.
I believe the X uses the XL length frame but with the 3.1" slide. They used to come with 3 magazines but I'm seeing the current tacpac might come with only two. That's worth 50 bucks if you can find an older package with 3 magazines in stock somewhere.
The X has the sight plate if you ever decide you want a red dot. Better to have that option than not I would say.
Probably the most common upgrade to the 365 is adding a flat trigger. The X comes that way from the factory. That's 42 bucks for the parts and an installation charge if you don't do it yourself.
The only downside I've found so far to owning a 365 series pistol is loading the magazines. My wife couldn't load more than 6 or 7 and I had difficulty going past 10. I solved that problem by getting two of these:
They're rated +P and I've fired some through mine without issues when that was all I could find.
The X and XL butt is slightly longer so won't accept 10round magazines if that's a problem where you live.
12round individual factory magazines come with two baseplates; one extended to use with the 10round frame and one "flush" to use with the 12round frame. My wife prefers the flush 10round magazines while I use the 12round with the extended baseplate. Both setups work in either standard 365 pistol. 15round magazines also come with two baseplates for the same reason.
I believe the X and XL pistols only come with the flat trigger. So I guess if you want a curved trigger then you'll have to put one on it. If I was buying a X type pistol I'd shoot it for a while before deciding to change triggers. I'm thinking about ordering a flat trigger for mine and if my wife likes it putting one on both.
S&W, Kimber, Ruger, SIG, Springfield and a few others are all making micro 9mm pistols now. Might be worthwhile to go to a gun range and rent a few different ones to see which works best for you and your grip/shooting style.
I carry a P365 (standard) every day with the 12rd mag in pistol and a 15rd in a side car. I added a Holosun 507K red dot. If you ever think you'll get a red dot, get the P365X which has an optic cutout already. It saves the hassle of sending your slide off to be cut and re-nitrided.
The up lula posted above is a must for loading the mags to their full capacity, but only the first couple times, after you've loaded them and let them sit for a few days, they can be loaded by hand. It does still get a bit tight at the end, but doable. The up lula is a fantastic tool either way.
I wouldn't buy the tac pac, the holster that comes with it is atrocious, and a standard 365 comes with two magazines, so you don't get anything fantastic for the tac pac price.