There's always the XPS 13 developer edition
Which is far from a completed product.
The first time we got it, suspend didn't work. You could suspend it, and resuming worked 50% of the time. The other 50% you had issues. A software update later fixed this.
Then there's boot time. Most PCs with 14.04 pretty much get you to the login prompt within seconds. It took a couple of minutes, despite it having a super fast SSD and a fast processor. Again, software update fixed this later.
The next time, the screen is high res. Linux and high res support is iffy, at best. It works, but if you plug in an external monitor, it too would be runing in high-res mode. It takes a bit of voodoo to get independent display scaling to work.
The next one was a software update. Which broke wifi, bluetooth and audio. Turns out Canonical turned on driver signing which broke all those drivers. Yeah, it's an easy fix (turn off secure boot), but still.
Yes, it's great, but damn are there serious usability issues.
We bought these things so we had reasonably powerful Linux certified laptops for developers to use so we internally didn't have to try the hit or miss process with regular Windows laptops.
In the end, we gave up and switched to Lenovo, whose machines seem to run Linux the best and have had fewer issues with breakage.