The more premium Xperia X phones aren't that great, to be honest. The budget end of the spectrum seems easier to justify, though. The Xperia XA Ultra just launched in the US recently and it's already on sale through Amazon for $312. It's usually $370.
The Xperia XA Ultra might appeal to you a bit more because it's not just a differently specced version of the Xperia X. This device has a huge 6-inch 1080p borderless display and a 16MP front-facing camera. Around back is a 21MP camera and inside is a MediaTek Helio P10 SoC, 3GB of RAM, and 16GB of storage.
Unfortunately, the only version of this phone on sale is the black one. The gold and white are still almost $60 more expensive. It's unlocked and compatible with North American GSM/LTE networks.