The choices are getting larger in the book department. Most people automatically disregard the eReader stating it's not for them, but really, they should not be so quick to judge. Let's go through them one at a time:
Hardback: this tends to be the most bulky, and the priciest. However, it also tends to last the longest, and unless you get unlucky, it looks the best. A lot of the series that I really like I try to get in the style, not all, but most. I also try to get the classics I am trying to collect and hardback.
Paperback: With paperback, you have two different types -- or are there more? I forget -- I know for sure of mass-market and trade. The mass-market are more ready available and are cheaper, usually ranging around eight dollar mark. The trade paperbacks tend to be more expensive and sometimes bookstores do not like to stock them, or they are harder to find. Mass-market are smaller, more standard size. Trade paperbacks are larger.
eReader/digital: range in price, but can be very cheap. They're stored on a single drive, or an extended drive and you can hold hundreds, if not thousands, of them on a single digital Reader. You can enlarge the font, you can change the orientation, and you can put your own documents on the Reader. It is very versatile. The benefit over hardback or paperback is you can take as many books with you as you want without the added bulk or weight.
AudioBook: here you have the benefit of having someone read to you wherever you are, or whatever you are doing. I have not looked into AudioBooks much, but it seems to me that they can run about the same price as the printed book, maybe more maybe less, it depends on the publisher, author, and book. Just like anything else. I know many people who love AudioBooks -- this is not a personal favorite of mine though... it is nothing against them, or the authors, or anyone in the publication of them... I just don't care for recorded voices, in any shape or form -- even my own... especially my own.
Each of these forms of books has their own personalities, their own uses, and can be mixed and matched very well. I even have paperback and hardback of the same books... depending on if I want the book to look nice or not. Just because you have one form, does not mean you cannot own another. It may sound... excessive...obsessive... maybe even wasteful, but if you love books, you know where I'm coming from.
In addition, think of it this way, if you're afraid that bound books are going the way of the dinosaur because of the digital books, you can still support both. I am. I'm not rich... I'm not even poor. I live paycheck to paycheck with barely enough money to get by -- but I always, always, always will find money to buy books. And now, I will find money for bound and digital books... for entertainment and for my health -- because if I want to keep reading there are days that I must use the Reader.
So I guess the moral of this brief comparison is don't discount one form of book over another, and don't discount owning more than one form of the same book, you never know when I'll come in handy.