The better iPhone X model.

If you're contemplating purchasing the iPhone X, and want the most carrier compatibility, get the A1865 instead of the A1901.  You don't lose out on any LTE or HSPA or UMTS (AKA GSM) compatibility, and you also gain the CDMA radio.

Here's the reference from Apple's Technical Spec page for the iPhone X.

As can be seen here, there's nothing to lose and potentially a lot to gain by getting the CDMA model. If you're buying the phone outright, it's a no-brainer here.

PROS

• You can use the device on all wireless carriers
• You gain CDMA compatibility
• Increases resale value because it can be used by customers of all wireless carriers

CONS

• You can't take advantage of carrier payment plan options

Let me know what you think.  I personally just picked up two of the Verizon A1865 models and activated them just fine using nothing more than my T-Mobile SIM.  Here's a picture of our Apple Store Camping adventure.  Before you go flaming me for not just pre-ordering online, it's because I'm not a Sprint or Verizon customer, and during pre-order you had to put carrier details in the order form whereas just buying it from the Apple Store did not require this.