I'm thinking of getting a laptop to run Linux on. I've heard Lenovo is generally well-supported (particularly models that come with Linux pre-installed).
Is there any particular hardware I should watch out for / avoid, and / or prefer? Any other brands / models people would particularly recommend?
Lenovo is always a safe bet, but definitely feel free to explore your options since Lenovo's are typically pricier. I use an HP with an Nvidia 16xx card and Intel processor and it runs a dream except for the annoyance of Optimus (running Intel graphics and Nvidia graphics at the same time). I've installed Linux on a lot of laptops, and I've only had issue with two models. The Dell Latitude E6430 ATG (finicky wifi and non-functional fingerprint reader) and the Panasonic Toughbook CF-52 (bluetooth no work).
Generally though anything is fine, especially if made in the last 5 years or so. Linux compatibility is really great these days. The biggest issues I'd be worried about is which wireless card it has, and if you need a fingerprint reader (especially if you get a Dell).
Some wireless cards won't automatically have their drivers installed no matter how hard you try (you have to do manual set up), and as far as I know, Dell fingerprint readers still don't work.