Check out Razer Blade or the Blade Pro, any Alienware, any System86 machine, most of the Dell XPS series. Don't touch HP with Linux (really bad firmware and driver compat issues).
I just bought a Razer blade and it has not been flawless with Ubuntu. Specifically, when I close the laptop lid, and then open it again, I keep getting logged out every ~15 seconds, until I restart the computer. As a work-around, I must manually suspend the laptop before closing the lid.
I have the Blade Stealth and haven't had any problems with it yet apart from an update that caused my fans to keep on spinning. It's been fixed since then.
I do agree that Linux has very variable performance and experiences across machines. I really do like the laptop though. I'm looking at the Razer Blade Pro (that machine is a beast but looks sexy still) and some Dell Precision laptops for an upgrade (will be passing on the Blade to my brother) but the Pro is extremely costly at the moment.
