The XPS 13 would've been my top choice if Dell were interested in taking my money, but they're only willing to sell me one with 16GB of RAM if it also has a pro-glare display. I bought an XPS 15, which came with major backlight bleed. After field circus scheduled an appointment to replace the display the next day and didn't show, I returned it.
I paid $500 less for my X1C5, bought during the Black Friday sale. It doesn't have a dGPU (that I didn't want anyhow); but does have a WQHD display, WWAN, and a 1 TB Samsung SSD instead of a 512 GB Toshiba. No issues with Linux or OpenBSD, and the keyboard is better than both the current XPS 15/Precision 5520 and my 2013 rMBP 13". (Let's not even think about how hard the current MBPs suck.)
I paid $500 less for my X1C5, bought during the Black Friday sale. It doesn't have a dGPU (that I didn't want anyhow); but does have a WQHD display, WWAN, and a 1 TB Samsung SSD instead of a 512 GB Toshiba. No issues with Linux or OpenBSD, and the keyboard is better than both the current XPS 15/Precision 5520 and my 2013 rMBP 13". (Let's not even think about how hard the current MBPs suck.)