I personally like the kindle as I have the kindle 3g. It is quick, small, has great battery life and also great customer service. I love the amazon store as well. I have played with one of the older kobos at a Borders and just didn't really like it although they have changed since then. I have used the web browser on the kindle in a pinch and it works well enough, although not as good as my ipad of course. I am pretty sure that it can go to sites like facebook.
As to purchasing books from other sites like the sony store ect, I do do that for my kindle. I use a free program called Calibre, which is a free ebook management program to organize all my books. It can also convert ebooks to all the various formats like epub, mobi, pdf, lit ect. The big thing with doing this is that in order to convert books from the different stores you have to remove the Drm. It isn't hard to do and a quick google search can show you how. The first thing I do when I purchase a book is remove the DRM. I have done this on Barnes and Noble, Smashwords, Amazon, ereader when it was around, Kobo, and the Sony Store. As soon as I remove the DRM, I convert the book to mobi and read on my kindle. This is cool, as I have taken advantage of kobo coupons and found books free on those sites that weren't free on Amazon.
Also, and I don't know how it works in Canada, I put library books on my kindle using the smae method. I remove the Drm, read the book, then delete from my computer and kindle. Now this might be in the shady part of DRM removal, as I could technically keep the book as by breaking the DRM I also remove the expiration on the book. I still abide by the rules, but I could see how that could be abused. Anyways, Kindle will be supporting library books later this year so that is like a nonpoint now.
I personally love my kindle, and find it a very flexible reader. Removing DRM opens up a lot of options on it, but this very thing would also open up the same options on the kobo as by again removing DRM, you wouldn't be tied to the Kobo store.
Hope you find the reader that fits you best,