E readers

With all the new e readers out like the kindle, nook and sonys ereader what is the best? what is the best for your money and what do you get out of having a ereader? Mitch from games has a kindle I am hoping to get him to post something on it soon. My main question i where does it lie amugst my devices I own a laptop and a umpc with a touch screen a blackberry storm and a zune hd. Where do e readers fit? Do I need one? Are they good for manuals or how to books? Becuse I am in IT and reader manuels or how to's and tons of pdfs so is a ereader good for me. I personaly dont think so I may buy one just to own it but I think my umpc does what it does and then some. I dont need a dedicated gadget for ebooks or pdf's (which ever one supports it) I think they are good maybe for moms or people that may travel by public transportastion becuse of the easier carring of more then one book.