12.5" Lenovo ThinkPad X270, base price of $999, but you will need to upgrade options to get the configuration you want. It has a built in ethernet port, and you can upgrade the RAM since it has a single RAM slot. The Dell XPS lacks the ethernet port and the RAM is soldered into the motherboard making it impossible for you to upgrade the RAM in the future. 4GB of RAM is really not a lot.
http://shop.lenovo.com/us/en/laptops/thinkpad/x-series/x270/
Upgrading to an i7-7500u will add $160. A 1080p screen with be an additional $200. A 180GB SATA interface SSD is $50 and that is the largest SSD they offer. I suggest you simply upgrade the CPU and the 1080p screen when you order it. Purchase your own SATA interface SSD of whatever capacity...