I had the same dilemma myself not long ago. IMO a single device should not multitask. You should get a tablet if and only if you will be moving a lot, you will need to prepare spreadsheets, write documents, prepare slides, check email and all that shit without having to carry a large computer around. And even then I'd choose a netbook (Asus eeePC, Acer Aspire One, why didn't netbooks catch on?) over a tablet most of the time. An eReader is only good for 1 thing - reading books. That's what it was invented for and only choose this if you wish to read books and nothing more on a tablet-sized thing.
Now comes into mind - which model to choose. Ofcourse the Kindle has gone mainstream (probably for a really good reason) and I will get one eventually, because it only does 1 thing - lets you read books. That's it. There are those PocketBook bullshit readers and others that compete with each other by adding really unneeded features. IMO a device like an ebook reader should NOT have unrelated features to distract the reader.
A Kindle doesn't have all that crap, only wifi support and in newer models an experimental internet browser. While PocketBook and others offer a fucking touchscreen, music player comes with speakers built-in, a full internet browser, basically a tablet with epaper screen. That is garbage. The more features you have the more you'll want to drop the book and go do something more entertaining, you'll go read some website or try and listen to music on your device or something else.
Kindle doesn't have all that and that's why it's great.
But what I don't really like about eReaders is that they come in very small screens. Reading a normal book on it becomes unnatural, and with a pdf-reflow as RBA said, code samples and other text blocks that should not be reflown become unreadable. AFAIK Kindle doesn't offer bigger screens and that is kind of a bummer.
I myself can't stand reading a book on a computer, I cannot get comfortable with the screen and position I sit and I am just that kinda person that cannot sit calm on a computer and read. The computer screen isn't designed to look at for many hours. ePaper screen has few advantages over the capacitive tablet screen. For one it doesn't give a fuck about bright sun cumming on your screen, the screen is as visible in sunlight as if a paper book. The screen doesn't glare and only use battery energy when repainting the screen (flipping a page etc.). As some reviews said, if you would read a Kindle for 1 hours every day, the fully charged battery would last for a month (or so...).
So tl;dr, get an ereader if you will only read books on it. Get a tablet if you choose to multitask on it. Remember that you can always check video tutorials on a computer. With coding/CS you will most likely watch whole series or video tutorials, and the tablet won't last that long anyway.
