Which e reader?

I have decided to take the plunge and purchase an e reader. I have been purchasing short stories online from a variety of e-publishers and I would like to be able to read a novel online without being tied to the laptop. 

My favorite epublishers ( publishers who primarily publish electronic books) are the wild rose press, cobblestone press, breathless press, red rose press, and ellora's cave. I have found their short stories well written and entertaining. I would be honored and priviledged to have any one of them purchase and publish one of my short stories or one my novels.

Anyway, I am trying to figure out which type of e-book reader I should purchase. I am really interested in the ipad but I am afraid that it is too much like a laptop and I will be distracted by all the other things that I am able to do with it instead of reading. The entry level price of $499 is reasonable for a small laptop but since I already have full sized laptop and a netbook purse sized laptop I can't really justify another. Can I? It would be cool to be able to watch movies but I really want to focus on reading so it does seem a bit much.

The Kindle from Amazon seems to be the industry standard but I don't want to have to buy books from Amazon. I ususally do but I don't want to have to.

The Nook from Barnes and Noble seems to be a good option and from what I hear you can order books from other publishers. It also has some expandable sD card which may prove helpful in the future. I think that I heard the Nook has wifi capability which would be useful if I am inside the Barnes and Nobles store or at home. Unfortunately, they closed the huge Barnes and Nobles at Hilltop Mall. Sigh....so I will have to drive to El Cerrito or Emeryville to play with one before buying.

My mom has the Sony reader that she got free with her American Express points. So far she has been only reading the free books that came with the thing so she hasn't been able to tell me whether or not she can purchase books from online publishers or anything else about the thing. They have a good price on the Sony at Best Buy. It is really small and portable so that could be a plus.

I just don't know. Recommendations?