I lust after a Rytek keyboard. You seem to be able to plug it into your tablet / computer so that you can type as though on a keyboard. Drool drool swoon swoon swoon. I haven't actually touched one though so I don't actually know how good they are.
I have a Macbook, which we've had for a good five years and yes, it still runs brilliantly, but husband nicked it for his photography. It's a bit annoying to type though as there's no true delete key, just backspace, but I imagine that varies by model.
I have a chromebook which is brilliant for not getting clog-brain and slowing down, but but its brain has outlasted its body as its a bit cheap plastic. I did nanowrimo on it though and it was great as I could sneak it into work into the staff room.
I have scrivener on my asus vivobook which runs windows but it was affordable and the keyboard is very nice for typing on. As good if not better than our Sony Vaio which we bought in 2012 and which became quite quickly outdated (it's very heavy)
So long story short, asus vivobook for affordability. Rytek if you're a hipster. Macbook if you want true longevity. But if it's mostly for writing on, try to avoid going online on it and it will last longer as it will attract fewer cyber diseases.
Having said all of that, scrivener on the Mac was a whole world better than on Windows because the functionality is better on the Mac version. Moreover since you do get what you pay for, the screen on the Mac is an awful lot better than on anything cheaper, which I noticed when I switched - reading text on the Mac was so smooth (it's absolutely find on the vivobook but the mac... oh... husband, how dare you nick my mac)