I definitely prefer ebooks. Here's why (from a purely practical point of view):
1. Learning programming and other stuff from paperbooks just doesn't work - you can't search the book or scroll quickly though the pages, you can't change the size of the pages/font, you can't copy-paste code or take screenshots etc.. And if it's a paperback, good luck with keeping the book on the page you're on, or even keeping it open, without keeping one hand on it all the time (impossible if you're learning programming or stuff like that). And if you don't have much space on your desktop it gets in the way of the keyboard. With an ebook, just alt+tab to shift between ebook and IDE. Or keep them side by side, or use two monitors.
2. You can put as many high quality pictures as you like in an e-book without it getting more expensive to produce. Paperbooks are much more expensive to produce if they contain high quality color pictures.
3. You can produce as many copies of an e-book as you like at practically no cost. Each paperbook costs to produce, and the less copies, the more each copy costs.
4. You can send an ebook from one part of the world to another in an instant, at practically no cost. A paperbook has to be packed (well packed, if you want it to arrive undamaged), you have to go to the post office to send it, it often costs a lot to send, and it can take a long time before it arrives. Then there's customs fees - if I order a book from outside EU that cost more than $12 I have to pay a $25 VAT/customs processing fee for the first book and $5 for any additional books each. No such thing on ebooks.
5. If a paperbook gets lost, or if you spill coffee on it, you can't just get a new free copy from a backup. You have to pay for a brand new copy - if it's still available, and you can afford it (rare books can be very expensive).
6. Dogs, rodents and insects don't eat ebooks (viruses do sometimes, but then you have your backups, right?
7. Paper books take up a lot of space, which not everyone have a lot of. They weigh a lot - one million average paper books would weigh about 250 tons, one million ebooks on a DVD weigh less than 20 grams.
Paperbooks do have their advantages - you don't need en electronic device to read them, and people are less likely to steal them than to steal your Notebook, iPad or Kindle if you're on the beach or some other public place. It's also hard to make illegal copies of them, which is an advantage to the author. But that's all, at least for me.