I have a Toshiba Google Chromebook and I love it.
https://www.amazon.com/Toshiba-CB35-B3330-Chromebook-Celeron-Silver/dp/B00N99FV76/ref=dp_ob_title_ce I have one like this one.
I don't bother to use Microsoft Office, but you can. The rare times I need Windows, I just use the online Office through the school. They use Microsoft Office and Outlook, and all students have a basic version of it for free. But honestly, I don't need it that much. And you can download it onto the Chromebook free on some models. I've never had to do that, though.
Online storage as opposed to on the computer has been a huge lifesaver. I back up to Google Drive because then I can get to it from any computer, and have a copy of my work saved if the one on my computer goes pear-shaped. Teachers take "my computer crashed" as the new "the dog ate my homework", heh, so I better have it regardless of what my tech does. And between Google, SkyDrive, DropBox I have a ton of storage, so I don't need to pay for it in the computer.
Three things make a computer expensive: Storage, speed, and screen. Screen I'd say go for. Headaches because of staring at a crappy screen all night suck. Storage doesn't matter if you use cloud storage. And speed is only really necessary if he plays MMOs or other memory intense computer games.
The most important feature of a computer for me is weight. Chromebook is lighter than my notebooks, and since I'm carrying it around all day that is important. I brought a heavier computer before and my back got really sore really fast.
If he wants an Windows machine, I'd get a Toshiba transformer, that's lightweight. And Toshiba is the best out there. Samsung is close second. I've had their netbooks and they are good.
I don't know much about Apple computers, because they are hugely expensive and I use Google everything anyway.