I similarly had this dilemma when I was shopping around for a new ereader to replace my ancient PRS-500. The highest priority on my list was readability - I mean, that's the point of the ereader. My biggest qualm with my PRS-500 is how poorly some books that I download from...ahem...3rd party sites show up on the device - when I'm 200+ pages into a novel it really irks me when some texts are missing/screwed up at the end of the book. For me, Kindle 3 was the easiest to read.
To address the issue of import fees - I thought of it as sales tax which you would have to pay in Canada anyways. I got the 3G Kindle and the import fee was ~22, plus ~10 for shipping. Here in BC, if I were to buy the Kindle in a retail store, the sales tax is 15%, which would work out to ~28. Also, I received the Kindle *literally* a day and a half after I placed the order online. As Canadians, I don't think we are so much screwed by the import fees than we are constantly screwed by high sales tax; I attributed the extra cost to that. Plus, the Kindle showed up at my door and I didn't need to spend gas or hop on the bus to go get it.
All in all, I'm fairly happy with my Kindle. I do pay for books now but since I'm a fairly slow reader I only buy 2-3 books a month, and the authors are compensated for their work.