[estro]

I second the recommendation to get an Asus Zenbook, with the same cons. The case is solid and durable; specs range from reasonable to outstanding (especially at its price point). I would also look at the IBM Thinkpad, as I've had friends and coworkers praise its Linux interoperability.

[havemylife]

Seconding the Thinkpad. There's also various repurposed IBM (I want to say mostly T200 and T400) that have GNU/Linux and an open source bios (or boot loader, I apologise if I'm mixing terms) pre-installed.

Price is probably high for the hardware though I think it's goes back into further open-source libre development.

But if it is important to you, you'll actually 'own' your computer.

[krylon]

Pre-owned / refurbished ThinkPads can be found surprisingly cheaply on Amazon (and elsewhere, I suppose). If you value reliability over performance, formerly top-shelf ThinkPads provide that at a great price. I got a ~2011 x220 for about €230 a few years ago - works like a charm on Debian, and compared to what that money gets you in current hardware, it's still a kick ass machine - except for the low display resolution...