My first choice would be an iPad pro with the apple pencil because of how easy it is to write naturally on and take notes on, however, this is far too expensive for me.
I'm looking for an affordable tablet or note-taking device that I can take electronic handwritten notes on that actually works well.
Right now, I have a Lenovo Flex 2 which has a touch screen but styluses work terribly on it. I'm worried some tablets would have similar issues.
Go to your nearest office supply store. Look for lined 8.5x11 notepads. Buy one and a set of pens. I'm a big fan of Pilot's G2 pens, but I've recent started using fountain pens and love them, at least for use inside the office. For my briefcase I still use Pilots.
And no, I'm not being snarky. I grew up with computers and I love tech, but for note-taking, after four years of undergrad, three of law school, and now four years in practice, nothing beats paper and pen for notes. Tablets are great for media consumption but are still sh*t for productivity unless you spend a small fortune on a Surface Pro.
The Surface Pro is actually the better choice than any iPad. The original Pro is still a better option than the iPad, and not nearly as expensive as the current Surface Pro 4 or Surface Book. A Pro 3 is probably the best option at this point for cost and benefits. These use real pens, not styli, and you can write directly into OneNote or any other software you wish.
I do agree that the good old pen and paper is still faster. Once your page is completed, it is simple to scan it into OneNote or many other programs, even with your phone. You don't need a flatbed scanner any more for documents.